Youngsook Son

Publications of Youngsook Son

• Perspectives on mesenchymal stem cells: tissue repair, immune modulation, and tumor homing.

  Authors: Hyun Sook Hong, Yeong Hoon Kim, Youngsook Son

  Archives of pharmacal research. 02/2012; 35(2):201-11.

  Mesenchymal stem cells (MSCs) or MSC-like cells have been identified in a variety of different tissues that share molecular expression profiles and biological functions but also retain a uniqueMesenchymal stem cells (MSCs) or MSC-like cells have been identified in a variety of different tissues that share molecular expression profiles and biological functions but also retain a unique differentiation preference depending on their tissue origins. MSCs play beneficial roles in the healing of damaged tissue by directly differentiating to many different resident cell types and/or by secreting several trophic factors that aid tissue repair. Aside from MSCs' reparative stem cell function, they drive immune responses toward immunosuppression and anti-inflammation. This novel function of MSCs opens up new avenues for clinical development of MSC immune-therapeutics to treat uncontrollable, life threatening, severe, chronic inflammation and autoimmune disease. Unexpectedly high rates of MSCs' tumor homing capacity and their tumor supporting capability have also been noted in tumor-bearing animal models. In this review, we will discuss MSCs' basic cell biology and perspectives on MSCs in terms of tissue repair, immune modulation, and tumor homing.

• A new paradigm for stem cell therapy: substance-P as a stem cell-stimulating agent.

  Authors: Hyun-Sook Hong, Do Yeon Kim, Kang Jun Yoon, Youngsook Son

  Archives of pharmacal research. 12/2011; 34(12):2003-6.

  Bone marrow is a reservoir for hematopoietic stem cells, endothelial precursor cells, and bone marrow stromal cells (also generally called mesenchymal stem cells), whose positive role in tissueBone marrow is a reservoir for hematopoietic stem cells, endothelial precursor cells, and bone marrow stromal cells (also generally called mesenchymal stem cells), whose positive role in tissue repair is highly anticipated. In this report, we introduce a novel function of substance-P (SP), an 11-amino-acid peptide, as an injury-inducible messenger to mobilize bone marrow stem cells to the blood and finally to engage in tissue repair. This new drug may substitute for ex vivo cell culture of therapeutic cells by stimulating cell proliferation in the bone marrow in vivo and mobilizing those therapeutic cells to the patient's own blood stream. Again, the additional role of SP in mitigating inflammation-mediated tissue damage can further rationalize the clinical development of SP-peptide as a stem cell stimulant.

• Schwann-like cells from human melanocytes and their fate in sciatic nerve injury.

  Authors: Guang Fan Chi, Dae-wook Kim, Mei Hua Jiang, Kang Jun Yoon, Youngsook Son

  Neuroreport. 08/2011; 22(12):603-8.

  We induced human melanocyte dedifferentiation to Schwann cell-like cells in vitro by a combination of forskolin, neuregulin-β1, neurotrophin-3, platelet-derived growth factor-aa, basic fibroblastWe induced human melanocyte dedifferentiation to Schwann cell-like cells in vitro by a combination of forskolin, neuregulin-β1, neurotrophin-3, platelet-derived growth factor-aa, basic fibroblast growth factor, laminin, and heparin. Cultured human melanocytes constitutively expressed neural cell and melanocyte markers but melanocyte-specific marker, including microphthalmia-associated transcription factor and tyrosinase, expression was selectively lost after induction. In the sciatic nerve injury site, the induced cells were engrafted and closely aligned to axons and P0-expressing myelin sheaths, whereas uninduced cells were not colocalized with axons and myelin sheaths and reexpressed melanocyte-specific tyrosinase activity in vivo. Human melanocytes lose their melanocyte phenotype and transdifferentiate into Schwann cells under specific induction conditions and display their Schwann cell phenotype after transplantation to injured sciatic nerve tissue.

• Selective nanopatterning of protein via ion-induced focusing and its application to metal-enhanced fluorescence.

  Authors: Chang Gyu Woo, Hyuck Shin, Changui Jeong, Kimin Jun, Jungpyo Lee, Jung-Rok Lee, Heechul Lee, Sukbeom You, Youngsook Son, Mansoo Choi

  Small (Weinheim an der Bergstrasse, Germany). 05/2011; 7(13):1790-4.

• A strong promoter activity of pre-B cell stage-specific Crlz1 gene is caused by one distal LEF-1 and multiple proximal Ets sites.

  Authors: Sung-Kyun Park, Youngsook Son, Chang-Joong Kang

  Molecules and cells. 05/2011; 32(1):67-76.

  The promoter of pre-B cell stage-specific Crlz1 gene, whose protein translocates the cytoplasmic core binding factor β (CBFβ) into the nucleus and thereby allows its heterodimerization with Runx, hasThe promoter of pre-B cell stage-specific Crlz1 gene, whose protein translocates the cytoplasmic core binding factor β (CBFβ) into the nucleus and thereby allows its heterodimerization with Runx, has a very strong activity, which is about 25% of cytomegalovirus (CMV) promoter activity and comparable to the EF-1α promoter activity. Its transcription start site was mapped at 155 nt upstream of translation initiation codon. 5'-truncation analysis of charged amino acids rich leucine zipper 1 (Crlz1) promoter revealed that one distal region from -612 to -536 and one proximal region from -198 to -100 as numbered from the transcription start site were critical for the promoter activity. The 3'-truncation analysis of the promoter revealed that the basal promoter sequence around the transcription start site, which should be necessary for the assembly of transcription initiation complex and the start of RNA polymerase II, was also essential, although not sufficient by itself. When transcription factor binding sites within those two critical regions were searched by in vivo footprinting, one distal LEF-1 and multiple proximal Ets consensus-like sites were found to be footprinted. Indeed, the protein causing a footprint over the distal region was found to be LEF-1, and the ones causing three footprints over the proximal region were found to be such Ets family members as Fli-1 and GABP, as verified by EMSA and ChIP analyses. Furthermore, those LEF-1 and Ets sites were shown to drive additively a strong transcription of Crlz1 gene.

• A glycosidic spinasterol from Koreana stewartia promotes procollagen production and inhibits matrix metalloproteinase-1 expression in UVB-irradiated human dermal fibroblasts.

  Authors: Tae Hoon Lee, Sang Min Lee, Dae-Young Lee, Youngsook Son, Dae Kyun Chung, Nam-In Baek, Jiyoung Kim

  Biological & pharmaceutical bulletin. 01/2011; 34(5):768-73.

  Methanol extract of Koreana stewartia leaves (SKE) stimulated collagen production in ultraviolet-B (UVB)-irradiated human fibroblast cells. An active compound was isolated from SKE by successiveMethanol extract of Koreana stewartia leaves (SKE) stimulated collagen production in ultraviolet-B (UVB)-irradiated human fibroblast cells. An active compound was isolated from SKE by successive partitioning and chromatography, and the chemical structure was determined to be 3-O-β-D-glucopyranosylspinasterol (spinasterol-Glc) by spectroscopic characterization. Spinasterol-Glc increased collagen production in the supernatant of UVB-irradiated dermal fibroblast cell cultures in a dose-dependent manner. The effects of spinasteol-Glc on expression of procollagen and matrix metalloproteinase-1 (MMP-1) were further evaluated. We found that the compound stimulated collagen production in UVB-treated fibroblasts than in vehicle-treated control cells by about 3-fold. In addition, we also demonstrate that the compound increased the mRNA and protein levels of procollagen in UVB-treated fibroblast cells, while it inhibited expression of MMP-1. These results indicate that spinasterol-Glc protects fibroblast cells from the adverse effects of UV radiation via stimulation of procollagen synthesis as well as inhibition of MMP-1 expression. Spinasterol-Glc may be useful in the future development of therapeutic and cosmetic applications.

• Substance P stimulates the recovery of bone marrow after the irradiation.

  Authors: You Sun An, EunAh Lee, Mi-Hyun Kang, Hyun Sook Hong, Mi-Ra Kim, Won Seok Jang, Youngsook Son, Jae Youn Yi

  Journal of cellular physiology. 10/2010; 226(5):1204-13.

  The therapeutic use of ionizing radiation (e.g., X-rays and γ-rays) needs to inflict minimal damage on non-target tissue. Recent studies have shown that substance P (SP) mediates multiple activitiesThe therapeutic use of ionizing radiation (e.g., X-rays and γ-rays) needs to inflict minimal damage on non-target tissue. Recent studies have shown that substance P (SP) mediates multiple activities in various cell types, including cell proliferation, anti-apoptotic responses, and inflammatory processes. The present study investigated the effects of SP on γ-irradiated bone marrow stem cells (BMSCs). In mouse bone marrow extracts, SP prolonged activation of Erk1/2 and enhanced Bcl-2 expression, but attenuated the activation of apoptotic molecules (e.g., p38 and cleaved caspase-3) and down-regulated Bax. We also observed that SP-decreased apoptotic cell death and stimulated cell proliferation in γ-irradiated mouse bone marrow tissues through TUNEL assay and PCNA analysis. To determine how SP affects bone marrow stem cell populations, mouse bone marrow cells were isolated and colony-forming unit (CFU) of mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) was estimated. SP-pretreated ones showed higher CFUs of MSC and HSC than untreated ones. Furthermore, when SP was pretreated in cultured human MSC, it significantly decreased apoptotic cells at 48 and 72 h after γ-irradiation. Compared with untreated cells, SP-treated human MSCs showed reduced cleavage of apoptotic molecules such as caspase-8, -9, -3, and poly ADP-ribose polymerase (PARP). Thus, our results suggest that SP alleviates γ-radiation-induced damage to mouse BMSCs and human MSCs via regulation of the apoptotic pathway.

• A new 3D reconstituted human corneal epithelium model as an alternative method for the eye irritation test.

  Authors: Kyoung-Mi Jung, Su-Hyon Lee, Yang-Hwan Ryu, Won-Hee Jang, Haeng-Sun Jung, Ju-Hee Han, Seung-Hyeok Seok, Jae-Hak Park, Youngsook Son, Young-Ho Park, Kyung-Min Lim

  Toxicology in vitro : an international journal published in association with BIBRA. 10/2010; 25(1):403-10.

  Many efforts are being made to develop new alternative in vitro test methods for the eye irritation test. Here we report a new reconstructed human corneal epithelial model (MCTT HCE model) preparedMany efforts are being made to develop new alternative in vitro test methods for the eye irritation test. Here we report a new reconstructed human corneal epithelial model (MCTT HCE model) prepared from primary-cultured human limbal epithelial cells as a new alternative in vitro eye irritation test method. In histological and immunohistochemical observation, MCTT HCE model displayed a morphology and biomarker expressions similar to intact human cornea. Moreover, the barrier function was well preserved as measured by high transepithelial electrical resistance, effective time-50 for Triton X-100, and corneal thickness. To employ the model as a new alternative method for eye irritation test, protocol refinement was performed and optimum assay condition was determined including treatment time, treatment volume, post-incubation time and rinsing method. Using the refined protocol, 25 reference chemicals with known eye irritation potentials were tested. With the viability cut-off value at 50%, chemicals were classified to irritant or non-irritant. When compared with GHS classification, the MCTT HCE model showed the accuracy of 88%, sensitivity of 100% and specificity of 77%. These results suggest that the MCTT HCE model might be useful as a new alternative eye irritation test method.

• Schwann cells differentiated from spheroid-forming cells of rat subcutaneous fat tissue myelinate axons in the spinal cord injury.

  Authors: Guang Fan Chi, Mi-ra Kim, Dae-Wook Kim, Mei Hua Jiang, Youngsook Son

  Experimental neurology. 04/2010; 222(2):304-17.

  In the present study, we found that nestin-expressing spheroid cells derived from multipotent adipose stem cells of subcutaneous fat tissue could efficiently differentiate into Schwann cells (SCs) inIn the present study, we found that nestin-expressing spheroid cells derived from multipotent adipose stem cells of subcutaneous fat tissue could efficiently differentiate into Schwann cells (SCs) in vitro based on expression of SC markers such as A2B5, GFAP, O4, p75, S100, Sox10, Krox-20, and L1. The induced SC is engrafted to spinal cord injury lesions and formed a peripheral nervous system (PNS)-type myelin sheath on central nervous system (CNS) axons. PNS-type myelin sheath formation in repaired tissue was confirmed by transplantation of both induced PKH26-labeled SC and induced EGFP-expressing SC generated from EGFP transgenic rats. In addition to direct participation as myelin sheath-forming SC in repaired tissue, the induced SC also expressed several neurotrophic factors, as did native SC, which may suggest an additional role for induced SC in stimulation of endogenous healing responses. Thus, spheroid-forming cells from subcutaneous fat tissue demonstrated rapid and efficient induction into SC, and such cells show therapeutic promise for repair of damage to the CNS and PNS.

• Ocular Surface Reconstruction with Autologous Nasal Mucosa in Cicatricial Ocular Surface Disease.

  Authors: Jae Hoon Kim, Yeoun Sook Chun, Seok-Hyun Lee, Seog Kyun Mun, Haeng Sun Jung, Su Hyon Lee, Youngsook Son, Jae Chan Kim

  American journal of ophthalmology. 10/2009;

  PURPOSE: To investigate the possibility of replacing the metaplastic ocular surface with nasal mucosa, and to evaluate the results of autologous nasal and oral mucosal transplantation in cicatricialPURPOSE: To investigate the possibility of replacing the metaplastic ocular surface with nasal mucosa, and to evaluate the results of autologous nasal and oral mucosal transplantation in cicatricial ocular surface diseases. DESIGN: Retrospective interventional case series. METHODS: We studied 6 eyes in 6 patients with chemical burns, which were characterized by a cicatricial ocular surface. After removal of cicatricial tissues and symblepharolysis, autologous nasal mucosa was transplanted in all patients. In 3 patients with extensive damage, oral mucosal autografting was performed concurrently. The nasal and oral mucosa was evaluated using immunohistochemical analysis for p63, K3, MUC5AC, and CD34. Clinical outcomes were assessed based on visual acuity, ocular manifestations, and liquid-based cytology. RESULTS: Immunohistochemical analysis revealed a plentitude of p63 and K3 in nasal mucosal epithelium. Goblet cells and MUC5AC expression were only observed in nasal mucosal epithelium, not in oral mucosal epithelium. Well-developed parallel vasculature was demonstrated in the nasal mucosa. In contrast, perpendicular vasculature was demonstrated in the oral mucosa. This vascular feature remained after transplantations. In all patients, ocular surface stability recovered with no major complications and increased goblet cells were observed on ocular surface. However, delayed epithelialization and ischemic thinning were seen at oral mucosal graft sites. CONCLUSIONS: Nasal mucosa, which has the advantage of well-developed parallel vasculature, enriched goblet cells, and plenty of stem cells, may be an ideal substitute for a cicatricial ocular surface. Transplantation of autologous nasal mucosa is a very effective method for achieving ocular surface reconstruction in cicatricial ocular surface diseases.

• Transforming growth factorbeta(1) transactivates EGFR via an H(2)O(2)-dependent mechanism in squamous carcinoma cell line.

  Authors: EunAh Lee, Jae Youn Yi, Eunkyung Chung, Youngsook Son

  Cancer letters. 09/2009;

  TGFbeta is known to transactivate EGFR. However, the signaling component involved in this crosstalk has yet to be revealed. Here, we found that TGFbeta(1) phosphorylated EGFR in a dose-dependentTGFbeta is known to transactivate EGFR. However, the signaling component involved in this crosstalk has yet to be revealed. Here, we found that TGFbeta(1) phosphorylated EGFR in a dose-dependent manner in SCC13 and A431 cells, and it was not blocked by EGF-neutralizing antibody. H(2)O(2) was increased by TGFbeta(1) treatment in the same time-kinetics as EGFR activation. Pretreatment of N-acetyl cysteine abolished TGFbeta(1)-induced H(2)O(2) induction and EGFR activation. Direct treatment of H(2)O(2) phosphorylated EGFR and catalase inhibitor prolonged TGFbeta(1)-induced EGFR activation. These results show that TGFbeta(1) activates EGFR via an H(2)O(2)-dependent mechanism, which subsequently leads to the activation of Erk(1/2).

• CCL23 up-regulates expression of KDR/Flk-1 and potentiates VEGF-induced proliferation and migration of human endothelial cells.

  Authors: Kyu Yeon Han, Chan Woo Kim, Tae-Hoon Lee, Youngsook Son, Jiyoung Kim

  Biochemical and biophysical research communications. 05/2009; 382(1):124-8.

  CCL23 is a CC chemokine and exerts its biological activities on endothelial cells as well as on immune cells through CCR1. We investigated the potential effect of CCL23 on expression of KDR/Flk-1CCL23 is a CC chemokine and exerts its biological activities on endothelial cells as well as on immune cells through CCR1. We investigated the potential effect of CCL23 on expression of KDR/Flk-1 receptor in endothelial cells. PCR, confocal microscope and Western blot analysis revealed that CCL23 up-regulated KDR/Flk-1 mRNA and protein levels in endothelial cells. A reporter assay indicated that CCL23-induced KDR/Flk-1 expression primarily occurred at the transcriptional level. In addition, CCL23 stimulated phosphorylation of SAPK/JNK, and an inhibitor of SAPK/JNK blocks the CCL23-induced KDR/Flk-1 expression. Furthermore, VEGF-induced ERK phosphorylation was stimulated by CCL23. Finally, CCL23 promoted VEGF-induced endothelial proliferation and migration, which were correlated with the maximal stimulation of KDR/Flk-1 expression by CCL23. Taken together, these findings suggest that CCL23 results in up-regulation of KDR/flk-1 receptor gene transcription and protein expression and that KDR/Flk-1 up-regulation induced by CCL23 may contribute to potentiation of VEGF action in angiogenesis.

• A new role of substance P as an injury-inducible messenger for mobilization of CD29(+) stromal-like cells.

  Authors: Hyun Sook Hong, Jungsun Lee, EunAh Lee, Young Sam Kwon, Eunkyung Lee, Woosung Ahn, Mei Hua Jiang, Jae Chan Kim, Youngsook Son

  Nature medicine. 05/2009; 15(4):425-35.

  Tissue injury may create a specific microenvironment for inducing the systemic participation of stromal-like cells in the repair process. Here we show that substance P is an injury-inducible factorTissue injury may create a specific microenvironment for inducing the systemic participation of stromal-like cells in the repair process. Here we show that substance P is an injury-inducible factor that acts early in the wound healing process to induce CD29(+) stromal-like cell mobilization. Likewise, mobilization of such cells also occurs in uninjured mice, rats and rabbits if substance P is intravenously injected. Upon further characterization these substance P-mobilized CD29(+) cells were found to be similar to stromal cells from a number of connective tissues, including bone marrow (that is, bone marrow stromal cells, or BMSCs). Both substance P injection and transfusion of autologously derived substance P-mobilized CD29(+) cells from uninjured rabbits accelerated wound healing in an alkali burn model. Also, epithelial engraftment of the transfused cells into the injured tissue occurred during the wound healing. Finally, using human BMSCs as a test population, we show that substance P stimulates transmigration, cell proliferation, activation of the extracellular signal-related kinases (Erk) 1 and 2 and nuclear translocation of beta-catenin in vitro. This finding highlights a previously undescribed function of substance P as a systemically acting messenger of injury and a mobilizer of CD29(+) stromal-like cells to participate in wound healing.

• Comparison of articular cartilage with costal cartilage in initial cell yield, degree of dedifferentiation during expansion and redifferentiation capacity.

  Authors: Jungsun Lee, Eunkyung Lee, Hwi-yool Kim, Youngsook Son

  Biotechnology and applied biochemistry. 12/2007; 48(Pt 3):149-58.

  Costal cartilage has been proposed as an alternative donor of chondrocytes for articular-cartilage repair. In the present study we compared the initial cell yield of chondrocytes from rabbit costalCostal cartilage has been proposed as an alternative donor of chondrocytes for articular-cartilage repair. In the present study we compared the initial cell yield of chondrocytes from rabbit costal cartilage and their cell expansion rates in monolayer culture with those of articular cartilage. Costal cartilage gave an approx. 2.6-fold higher cell yield than did articular cartilage. During in vitro culture, CCs (costal chondrocytes) grew faster and displayed approx. 3-fold more cell expansion up to P4 (passage 4) than did ACs (articular chondrocytes). In order to match the degree of dedifferentiation during serial cultivation with the cells' expansion rate, type II collagen expression and the emergence of fibroblastic morphology were monitored at each cell passage. Both ACs and CCs gradually lost their chondrocytic phenotype, changed to fibroblast-like cells and displayed a reduced expression of type II collagen. We then also evaluated the redifferentiation capacity of the expanded ACs and CCs by culturing them at high density in collagen gel. Almost fully dedifferentiated CCs at P4 were successfully redifferentiated into hyaline cartilage, which showed the expression of glycosaminoglycan and type II collagen as well as the formation of lacunae and a territorial matrix. In conclusion, costal cartilage may have advantages over articular cartilage as an alternative donor tissue for autologous chondrocytes on the basis of its higher cell yield, higher cell expansion and successful reversion into hyaline cartilage without ossification in vitro. However, although this experiment with a rabbit model gave a better insight into the problem than other experiments have done, it does not answer definitively the question as to which cells are most appropriate for articular cartilage repair in humans.

• Diffusion of bioactive molecules through the walls of the medial tissue-engineered hybrid ePTFE grafts for applications in designs of vascular tissue regeneration.

  Authors: Insup Noh, Yoon-Jeong Choi, Youngsook Son, Chun-Ho Kim, Seung Hwa Hong, Choong Man Hong, In Soo Shin, Sue Nie Park, Beom-Young Park

  Journal of biomedical materials research. Part A. 12/2006; 79(4):943-53.

  Strategies of better vascular tissue engineering may require delivery of soluble bioactive signals in cell culture medium to the cells in tissue-regenerating constructs. We measured the diffusivityStrategies of better vascular tissue engineering may require delivery of soluble bioactive signals in cell culture medium to the cells in tissue-regenerating constructs. We measured the diffusivity and permeability of model tissue-engineering bioactive molecules such as water and heparin through the walls of both a hybrid ePTFE graft and a porcine carotid artery, a model vascular tissue. While diffusivities of H(3)-water and H(3)-heparin were measured as 3.9 x 10(-) (6) and 1.6 x 10(-) (6) cm(2)/s in the artery, respectively, under diffusional circulation of cell culture medium through the lumens of the carotid arteries, their corresponding permeabilities were 4.7 x 10(-) (5) and 2.0 x 10(-) (5) cm/s. On the other hand, diffusivities of H(3)-water and H(3)-heparin were also measured as 5.1 x 10(-) (6) and 4.7 x 10(-) (6) cm(2)/s, respectively, in the tissue-engineered hybrid ePTFE grafts; their corresponding permeabilities were 5.1 x 10(-) (5) and 3.7 x 10(-) (5) cm/s. The hybrid graft tissues were engineered by replacing the biodegradable, porous poly(lactide-co-glycolide) layers coated on the ePTFE surfaces with smooth muscle cell-derived tissues for 6 weeks. We analyzed the morphologies of the artery and the engineered hybrid ePTFE tissues with scanning electron microscopy and H&E stains. While the artery had its typical structure properties with layers of intima, media and adventitia, the tissue-engineered ePTFE hybrid graft had two layers of engineered tissues on the inner and outer surfaces of the ePTFE. There were no significant differences among the luminal tissue morphologies of the test samples from the effects of diffusion flow applications, with minor changes on their luminal surfaces. The results of water and heparin diffusion experiments indicated that these bioactive molecules were well transported from the cell culture medium to the tissue-engineering cells, enough to support tissue regeneration. We hope that these transport results may elucidate the transport behaviors of soluble nutrient molecules and biological signals through the vascular constructs under tissue engineering processes.

• The side population cells in the rabbit limbus sensitively increased in response to the central cornea wounding.

  Authors: Ki Sook Park, Chae Ho Lim, Byung-Moo Min, Jae Lim Lee, Hee-Yong Chung, Choun-Ki Joo, Chan-Woong Park, Youngsook Son

  Investigative ophthalmology & visual science. 04/2006; 47(3):892-900.

  PURPOSE: Side population (SP) cells are known to reside in the limbus as putative corneal epithelial stem cells. This study was performed to demonstrate the presence and the characteristics of SPPURPOSE: Side population (SP) cells are known to reside in the limbus as putative corneal epithelial stem cells. This study was performed to demonstrate the presence and the characteristics of SP cells in the rabbit limbal epithelium and explore their sensitivity in response to the central cornea wounding. METHODS: To sort out the SP cells, freshly isolated rabbit limbal and central corneal epithelial cells were subjected to Hoechst 33342 dye efflux assay. For characterization of the sorted SP cells, RT-PCR analysis, semi-dry three-dimensional (3-D) cell culture, and transplantation in nude mice were performed. To explore wound sensitivity of the limbal SP cells, the rabbit central cornea was wounded by direct contact of a 6-mm paper disk soaked with 1 N NaOH, and changes in the population size of the SP cells and the colony-forming efficiency (CFE) was monitored on days 1, 2, and 5 after wounding. RESULTS: The SP cells were present in the rabbit limbal epithelium with an incidence of 0.73% +/- 0.14% (n = 8) and were smaller in cell size than the major population (MP) cells, quiescent in the cell cycle, and in the undifferentiated state. The SP cells were able to regenerate the cornea-like structure with basal enrichment of p63-positive cells by in vitro 3-D culture and in vivo transplantation, all of which were best achieved by the whole population (WP) of cells comprising SP and MP cells. After central cornea wounding, this rare population of the limbal SP cells increased in size fivefold on day 1 and then decreased on day 2. The transient increase in the SP cells was subsequently followed by the propagation of an increase in CFE in the limbal MP cells on day 2 and then in the corneal MP cells on day 5. In the hematopoietic colony-forming assay, the limbal SP cells gave approximately eightfold higher CFU than the limbal MP cells. CONCLUSIONS: The SP cells identified in the rabbit limbus are an undifferentiated and noncycling rare epithelial cell population, which sensitively respond to the central cornea wounding by their transient increase in the population size.

• Evaluations of blood compatibility via protein adsorption treatment of the vascular scaffold surfaces fabricated with polylactide and surface-modified expanded polytetrafluoroethylene for tissue engineering applications.

  Authors: Yoon-Jeong Choi, Sung Kwang Choung, Choong Man Hong, In Soo Shin, Sue Nie Park, Seung Hwa Hong, Han Ki Park, Young Hwan Park, Youngsook Son, Insup Noh

  Journal of biomedical materials research. Part A. 01/2006; 75(4):824-31.

  Blood compatibility was evaluated by short-term in vitro blood perfusion on candidate vascular scaffold surfaces of a biodegradable, porous polylactide scaffold and a chemically surface-modifiedBlood compatibility was evaluated by short-term in vitro blood perfusion on candidate vascular scaffold surfaces of a biodegradable, porous polylactide scaffold and a chemically surface-modified expanded polytetrafluoroethylene (ePTFE) over a clinical ePTFE, by measuring blood cell adhesion either directly or after adsorption treatment with albumin and fibrinogen. The results indicated that the extent of blood cell adhesion was affected by scaffold surface properties and pre-adsorption of proteins such as fibrinogen and albumin. Surface morphologies and porosity of the scaffolds were characterized by scanning electron microscopy and porosimetry, and the amount of fibrinogen and albumin adsorbed on the scaffolds was measured and verified by employing radiolabeled C(14) albumin and I(125) fibrinogen by a scintillation counter and a gamma counter, respectively. Even though treatment of fibrinogen adsorption on the samples in advance led to higher induction of blood cell adhesion than those with no fibrinogen adsorption, the polylactide scaffold surface itself induced highest amount of the adhered blood cells in this study judged by analyses of their surface area. These results would be employed as guidance in determining a choice of the implant methods, in vitro versus in vivo tissue engineering, of the novel chemically modified ePTFE and the biodegradable polylactide scaffolds.

• Inhibitory effect of rapamycin on corneal neovascularization in vitro and in vivo.

  Authors: Young Sam Kwon, Hyun Sook Hong, Jae Chan Kim, Jun-Seop Shin, Youngsook Son

  Investigative ophthalmology & visual science. 03/2005; 46(2):454-60.

  PURPOSE: To examine the effect of rapamycin on the proliferation and the migration of human umbilical vein endothelial cells (HUVECs) and on the corneal neovascularization in the corneal alkalinePURPOSE: To examine the effect of rapamycin on the proliferation and the migration of human umbilical vein endothelial cells (HUVECs) and on the corneal neovascularization in the corneal alkaline burn murine model. METHODS: HUVEC proliferation, migration, and apoptosis were examined after treatment with rapamycin. The effect of rapamycin on the mRNA expression of FK506 binding protein (FKBP)-12 and mammalian target of rapamycin (mTOR) was also evaluated in vitro. Corneal neovascularization was induced in vivo by an alkaline burn of the cornea with 1 N NaOH on BALB/c mice. Rapamycin was given intraperitoneally at 2 mg/kg body weight once a day for 12 days after the corneal alkaline burn. Growth factors and cytokines related with neovascularization and inflammation were evaluated in the corneal tissue and the peripheral blood by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The corneal neovascularization was evaluated by a slit lamp biomicroscopy. RESULTS: Rapamycin at the concentration of 1000 ng/mL for >48 hours' exposure significantly inhibited the growth of HUVECs. The double chamber assay showed that rapamycin dramatically inhibited the migration of HUVECs at concentrations of 10 and 100 ng/mL and that these concentrations did not affect endothelial cell growth. When TUNEL assays were performed, the number of apoptotic cells increased 1.9-, 2.1-, and 2.6-fold compared with the control at 10, 100, and 1000 ng/mL, respectively, of rapamycin at 48 hours of exposure. RT-PCR showed that the expression of mTOR was suppressed in the HUVECs after rapamycin treatment; however, FKBP-12 expression was not affected. Among the angiogenic factors, gene expression of substance P and hypoxia inducible factor (HIF)-1 alpha was inhibited by rapamycin earlier (1-3 days), with vascular endothelial growth factor (VEGFR)-1 gene expression being suppressed for the first 7 days in the corneal tissue. The protein level of substance P and vascular endothelial growth factor (VEGF) was significantly decreased--more in mice treated with rapamycin than the control mice--as shown by ELISA assay of peripheral blood. Furthermore, rapamycin significantly inhibited corneal neovascularization in the alkaline-burned cornea. CONCLUSIONS: Rapamycin strongly inhibited HUVEC migration at doses that did not cause cytotoxicity and apoptosis in this in vitro model. Rapamycin also suppressed corneal neovascularization, possibly by inhibiting proinflammatory cytokines, as shown by the in vivo study. Therefore, rapamycin may be useful as an angiogenic regulator in the treatment of corneal diseases that manifest with neovascularization.

• Novel role of substance-p as a systemic wound messenger to mobilize mesenchymal stem cell from bone marrow and be engaged in the wound healing epithelial layer

  Authors: Hyun Sook Hong, Jung Sun Lee, Young Sam Kwon, Eun Kyung Lee, Woosung Ahn, Jae Chan Kim, Youngsook Son

  Nature Precedings.

  Tissue injury may bring up the systemic participation of bone marrow stem cells in the repair. In this study, we report that substance-p is a systemically acting messenger to mobilize mesenchymalTissue injury may bring up the systemic participation of bone marrow stem cells in the repair. In this study, we report that substance-p is a systemically acting messenger to mobilize mesenchymal stem cell (MSC) probably from the bone marrow and be engaged in the wound healing process. This was supported by the injury-inducible substance-p detection in the tissue and the peripheral blood and subsequent MSC mobilization in the alkali-burn rabbit eye model, whose kinetics were dependent on the wound size. Furthermore, i.v. injection of exogenous substance-p stimulated MSC mobilization in the uninjured rabbits and those mobilized cells showed multipotent differentiation capacity. We demonstrated that earlier substance-p elevation in the circulation by substance-p injection or transfusion of autologous PKH-labeled MSC mobilized by substance-p strongly accelerated the wound healing of the alkali-burned rabbit eye and the transfused MSCs were engrafted to the epithelial and stromal layer of the injured tissue, suggesting their epithelial transdifferentiation in the regenerating tissue. Finally, we showed that substance-p stimulated transmigration of human MSC with concomitant induction of MMPs and inhibition of their inhibitors, cell proliferation, ERK1/2 activation, and nuclear translocation of [beta]-catenin _in vitro_. In conclusion, substance-p plays a role as a systemic wound-messenger to promote the MSC mobilization from the marrow and their participation in the wound healing possibly through its stimulant effect on MSC repopulation as well.

• Schwann cells differentiated from spheroid-forming cells of rat subcutaneous fat tissue myelinate axons in the spinal cord injury

  Authors: Guang Fan Chi, Mi-ra Kim, Dae-Wook Kim, Mei Hua Jiang, Youngsook Son

  Experimental Neurology.

  In the present study, we found that nestin-expressing spheroid cells derived from multipotent adipose stem cells of subcutaneous fat tissue could efficiently differentiate into Schwann cells (SCs) inIn the present study, we found that nestin-expressing spheroid cells derived from multipotent adipose stem cells of subcutaneous fat tissue could efficiently differentiate into Schwann cells (SCs) in vitro based on expression of SC markers such as A2B5, GFAP, O4, p75, S100, Sox10, Krox-20, and L1. The induced SC is engrafted to spinal cord injury lesions and formed a peripheral nervous system (PNS)-type myelin sheath on central nervous system (CNS) axons. PNS-type myelin sheath formation in repaired tissue was confirmed by transplantation of both induced PKH26-labeled SC and induced EGFP-expressing SC generated from EGFP transgenic rats. In addition to direct participation as myelin sheath-forming SC in repaired tissue, the induced SC also expressed several neurotrophic factors, as did native SC, which may suggest an additional role for induced SC in stimulation of endogenous healing responses. Thus, spheroid-forming cells from subcutaneous fat tissue demonstrated rapid and efficient induction into SC, and such cells show therapeutic promise for repair of damage to the CNS and PNS.