Fabian Muehlberg

University of Texas MD Anderson Cancer Center, Houston, TX, United States

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Publications (7)26.79 Total impact

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    ABSTRACT: It is unclear whether mesenchymal stem cells that are applied to regenerate wound tissues can migrate to existing tumors and enhance their growth. The authors investigated whether adipose-derived stem cells had any effect on the growth and progression of distant tumors when applied to a skin wound. The authors subcutaneously injected murine 4T1 breast cancer cells into all BALB/c-nu/nu mice. After tumor injection, mice were randomized to five groups (five mice per group) based on the means of co-introduction of green fluorescent protein-labeled adipose-derived stem cells, if any. In group 1, adipose-derived stem cells were combined and co-injected subcutaneously. In group 2, they were injected subcutaneously at a distant anatomical site. In group 3, they were injected intravenously. In group 4, they were delivered via a human acellular dermal matrix to a distant skin wound. In group 5, no adipose-derived stem cells were introduced. After 2 weeks, tumor volume increased in group 1 (356.5 ± 44.4 mm(3)), followed by group 3 (256.6 ± 47.1 mm(3)) and then group 2 (201.6 ± 28.6 mm(3)). In group 4, in which adipose-derived stem cells carried on acellular dermal matrix were applied to a wound distant to the primary tumor, the tumor volume was 143.8 ± 50.9 mm(3), which was similar to that observed in the control group (group 5; 167.8 ± 29.9 mm(3)). The authors' findings suggest that the wound microenvironment can retain adipose-derived stem cells, preventing their homing and stromal contribution to a distant neoplastic focus. These findings are an important first step in establishing the feasibility and safety of utilizing adipose-derived stem cell therapy for reconstructive surgery in the setting of malignancy.
    Plastic and reconstructive surgery 04/2011; 127(4):1467-77. · 2.74 Impact Factor
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    ABSTRACT: Recent evidence indicates that cancer stem cells play an important role in tumor initiation and maintenance. Additionally, the effect of tissue-resident stem cells located in the surrounding healthy tissue on tumor progression has been demonstrated. While most knowledge has been derived from studies of breast cancer cells, little is known regarding the influence of tissue resident stem cells on the tumor biology of prostate cancer. Twenty male athymic Swiss nu/nu mice (age: 6-8 weeks) were randomized into two treatment groups: (1) subcutaneous injection of 10(6) MDA PCa 118b human prostate cancer cells into the upper back or (2) subcutaneous injection of 10(6) MDA PCa 118b cells mixed directly with 10(5) GFP-labeled human adipose tissue-derived stem cells (hASCs). Tumor growth and volumes over the ensuing 3 weeks were assessed using calipers and micro-computed tomography. Immunohistochemistry was performed to identify engrafted hASCs in tumor sections. At 3 weeks after injection, the mean tumor volume in the MDA PCa 118b/hASC co-injection group (1019.95 ± 73.49 mm(3)) was significantly higher than that in the MDA PCa 118b-only group (308.70 ± 21.06 mm(3)). Engrafted hASCs exhibited the nuclear marker of proliferation Ki67 and expressed markers for endothelial differentiation, indicating their engraftment in tumor vessels. Our study revealed for the first time that ASCs subcutaneously co-injected with prostate cancer cells engraft and promote tumor progression. Further evaluation of the cross-talk between tumor and local tissue-resident stem cells may lead to new strategies for prostate cancer therapy.
    The Prostate 11/2010; 70(15):1709-15. · 3.84 Impact Factor
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    ABSTRACT: In the present study, we investigated whether human adipose tissue derived stem cells (hASCs) could enhance tumor invasion and whether these hASCs could be a potential source of CCL5. We observed a significant increase in the number of breast cancer cells that invaded the matrigel when Co-cultured with hASCs. We found that hASCs produce CCL5 in the Co-culture and cancer cell invasion was diminished by an antibody against CCL5. Furthermore, cancer cell invasion in the Co-culture was associated with an elevated level of MMP-9 activity. We conclude that CCL5 plays a crucial role for tumor invasion in the interplay of tissue resident stem cells from the fat tissue and breast cancer cells.
    Cancer letters 06/2009; 284(1):80-5. · 4.86 Impact Factor
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    ABSTRACT: Stem cells have been found to be involved in breast cancer growth, but the specific contribution of cancer stem cells in tumor biology, including metastasis, is still uncertain. We found that murine breast cancer cell lines 4T1, 4TO7, 167Farn and 67NR contains cancer stem cells defined by CXCR4 expression and their capability of forming spheroids in suspension culture. Importantly, we showed that CXCR4 expression is essential for tumor invasiveness because both CXCR4 neutralizing antibody and shRNA knockdown of the CXCR4 receptor significantly reduced tumor cell invasion.
    Cancer letters 04/2009; 280(1):65-71. · 4.86 Impact Factor
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    ABSTRACT: Mesenchymal stem cells derived from bone marrow have recently been described to localize to breast carcinomas and to integrate into the tumor-associated stroma. In the present study, we investigated whether adipose tissue-derived stem cells (ASCs) could play a role in tumor growth and invasion. Compared with bone marrow-derived cells, ASCs as tissue-resident stem cells are locally adjacent to breast cancer cells and may interact with tumor cells directly. Here, we demonstrate that ASCs cause the cancer to grow significantly faster when added to a murine breast cancer 4T1 cell line. We further show that breast cancer cells enhance the secretion of stromal cell-derived factor-1 from ASCs, which then acts in a paracrine fashion on the cancer cells to enhance their motility, invasion and metastasis. The tumor-promoting effect of ASCs was abolished by knockdown of the chemokine C-X-C receptor 4 in 4T1 tumor cells. We demonstrated that ASCs home to tumor site and promote tumor growth not only when co-injected locally but also when injected intravenously. Furthermore, we demonstrated that ASCs incorporate into tumor vessels and differentiate into endothelial cells. The tumor-promoting effect of tissue-resident stem cells was also tested and validated using a human breast cancer line MDA-MB-231 cells and human adipose tissue-derived stem cells. Our findings indicate that the interaction of local tissue-resident stem cells with tumor stem cells plays an important role in tumor growth and metastasis.
    Carcinogenesis 02/2009; 30(4):589-97. · 5.64 Impact Factor
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    ABSTRACT: A synthetic peptide representing the receptor-binding domain of human thrombin (TP508) promotes angiogenesis and accelerates wound healing in animal models. However, the mechanisms underlying the therapeutic effects of TP508 have not been clearly defined. In this study, we set out to determine whether TP508 could stimulate stem cell proliferation. Adipose tissue-derived stem cells (ASCs) were incubated with TP508 (5 microg/ml) and cell proliferation was determined by bromodeoxyuridine (BrdU) incorporation. Our data showed that TP508 treatment significantly stimulated BrdU incorporation in ASCs (p < 0.01). The increased BrdU incorporation induced by TP508 was abolished by the PI3 kinase (PI3K) inhibitor LY294002 at 50 microM. Western blot analysis of ASCs revealed increased phosphorylation of Akt in response to TP508 when compared to unstimulated controls. These results indicate that TP508 exerts proliferative effects on ASCs via the PI3K/Akt pathway.
    Journal of Vascular Research 08/2008; 46(2):98-102. · 2.43 Impact Factor
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    ABSTRACT: The objective of our study was to determine whether TNFalpha can protect tissue resident stem cells from hydrogen peroxide (H(2)O(2)) induced apoptosis. Apoptosis was measured via fluorescence activated flow cytometry of fluorescein-conjugated Annexin V in passage 3 human ASCs. Our data show that application of 300muM H(2)O(2) for 3h induced a high number of cells to undergo apoptosis. The number of apoptotic cells significantly decreased when cells were preincubated with TNFalpha. TNFalpha caused a rapid activation of NF-kappaB within 15min as evidenced by gel shift assay (EMSA). On further dissection of the NF-small ka, CyrillicB complex, the p50 subunit which generally forms heterodimers with p65 appears to form a p50/p50 homodimer instead of conventional p50/p65 heterodimer. This novel finding has implications for tissue regeneration and might as well be of importance for cancer cell growth and tumor progression.
    Biochemical and Biophysical Research Communications 08/2008; 371(4):626-9. · 2.41 Impact Factor