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Article: Shape Fidelity of Native and Engineered Human Nasal Septal Cartilage.
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ABSTRACT: Objective To test engineered and native septal cartilage for resistance to deformation and remodeling under sustained bending loads and to determine the effect of bending loads on the biochemical properties of constructs.Study DesignProspective, basic science.SettingLaboratory.Subjects and Methods Human septal chondrocytes from 6 donors were used to create 12-mm constructs. These were cultured for 10 weeks and subjected to bending for 6 days. Free-swelling controls and native tissue from 6 donors were used for comparison. Shape retention, photo documentation, live-dead staining, and biochemical properties were measured.ResultsLive-dead staining showed no difference in cell survival between loaded constructs and free-swelling controls. The immediate shape retention of the constructs was 39.0% versus 24.4% for native tissue (P = .13). After 2 and 24 hours of relaxation, the constructs possessed similar shape retention to native tissue (26.9% and 16.4%; P = .126; 21.7% and 14.4%; P = .153). There was no significant change in construct shape retention from immediately after release to 2 hours of relaxation (39.0% and 26.9%, respectively; P = .238). In addition, the retention did not change significantly between 2 and 24 hours of relaxation (26.9% and 21.7%; P = .48). There was no significant difference in biochemical properties between loaded constructs and controls.Conclusion The shape retention properties of human septal neocartilage constructs are comparable to human native septal cartilage. In addition, mechanical loading of neocartilage constructs does not adversely affect cell viability or biochemical properties. This study demonstrates that neocartilage constructs possess adequate shape fidelity for use as septal cartilage graft material.Otolaryngology Head and Neck Surgery 02/2013; · 1.72 Impact Factor -
Article: Flexural Properties of Native and Tissue-Engineered Human Septal Cartilage.
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ABSTRACT: Objective To determine and compare the bending moduli of native and engineered human septal cartilage.Study DesignProspective, basic science.SettingResearch laboratory.Subjects and Methods Neocartilage constructs were fabricated from expanded human septal chondrocytes cultured in differentiation medium for 10 weeks. Constructs (n = 10) and native septal cartilage (n = 5) were tested in a 3-point bending apparatus, and the bending moduli were calculated using Euler-Bernoulli beam theory.ResultsAll samples were tested successfully and returned to their initial shape after unloading. The bending modulus of engineered constructs (0.32 ± 0.25 MPa, mean ± SD) was 16% of that of native septal cartilage (1.97 ± 1.25 MPa).Conclusion Human septal constructs, fabricated from cultured human septal chondrocytes, are more compliant in bending than native human septal tissue. The bending modulus of engineered septal cartilage can be measured, and this modulus provides a useful measure of construct rigidity while undergoing maturation relative to native tissue.Otolaryngology Head and Neck Surgery 01/2013; · 1.72 Impact Factor -
Article: Morphology of the Cartilaginous Endplates in Human Intervertebral Disks with Ultrashort Echo Time MR Imaging.
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ABSTRACT: Purpose:To image human disk-bone specimens by using conventional spin-echo (SE) and ultrashort echo time (TE) techniques, to describe the morphology at magnetic resonance (MR) imaging, and to identify tissue components contributing to high signal intensity near the cartilaginous endplates (CEPs).Materials and Methods:This study was exempt from institutional review board approval, and informed consent was not required. Five cadaveric lumbar spines (mean age, 61 years ± 11) were prepared into six sample types containing different combinations of disk, uncalcified CEP, calcified CEP, and subchondral bone components and were imaged with proton density-weighted SE (repetition time msec/TE msec, 2000/15) and ultrashort TE (300/0.008, 6.6, echo-subtraction) sequences. Images were evaluated to determine the presence of intermediate-to-high signal intensity in regions excluding the bone marrow. Logistic regression was used to determine which tissue components were significant predictors of the presence of signal intensity for each MR technique.Results:On ultrashort TE MR images, intact disk/uncalcified CEP/calcified CEP/bone samples exhibited bilaminar intermediate-to-high signal intensity in the region near the CEP, consistent with the histologic appearance of uncalcified and calcified CEPs. Conversely, proton density-weighted SE images exhibited low signal intensity in this region. Results of logistic regression suggested that the presence of uncalcified CEP (P = .023) and calcified CEP (P = .007) in the sample were strong predictors of the presence of signal intensity on ultrashort TE images, whereas the disk was the only predictor (P < .001) of signal intensity on proton density-weighted SE images.Conclusion:Ultrashort TE imaging, unlike proton density-weighted SE imaging, enabled direct visualization of the uncalcified and calcified CEP. Evaluation of the morphology and identification of sources of signal intensity at ultrashort TE MR imaging provides opportunities to potentially aid in the understanding of degenerative disk disease.© RSNA, 2012.Radiology 11/2012; · 5.73 Impact Factor -
Article: Effect of autologous platelet-rich plasma-releasate on intervertebral disc degeneration in the rabbit anular puncture model: a preclinical study.
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ABSTRACT: INTRODUCTION: Platelet-rich plasma (PRP) is a fraction of plasma in which several growth factors are concentrated at high levels. The active soluble releasate isolated following platelet activation of PRP (PRP-releasate) has been demonstrated to stimulate the metabolism of IVD cells in vitro. The in vivo effect of PRP-releasate on degenerated IVD remains unknown. The purpose of this study was to determine the reparative effects of autologous PRP-releasate on degenerated intervertebral discs (IVDs). METHODS: To induce disc degeneration, New Zealand white rabbits (n=12) received anular puncture in two noncontiguous discs. Autologous PRP and PPP (platelet-poor plasma) were isolated from fresh blood using two centrifugation techniques. Four weeks after the initial puncture, releasate isolated from clotted PPP or PRP (PPP- or PRP-releasate), or phosphate-buffered saline (PBS; control) was injected into the punctured discs. Disc height, magnetic resonance imaging (MRI) T2-mapping and histology were assessed. RESULTS: Anular puncture produced a consistent disc narrowing within four weeks. PRP-releasate induced a statistically significant restoration of disc height (PRP vs. PPP and PBS, p<0.05). In T2-quantification, the mean T2-values of the nucleus pulposus (NP) and anulus fibrosus (AF) of the discs were not significantly different among the three treatment groups. Histologically, the number of chondrocyte-like cells was significantly higher in the discs injected with PRP-releasate compared to that with PBS. CONCLUSIONS: The administration of active PRP-releasate induced a reparative effect on rabbit degenerated IVDs. The results of this study suggest that the use of autologous PRP-releasate is safe and can lead to a clinical application for IVD degeneration.Arthritis research & therapy 11/2012; 14(6):R241. · 4.27 Impact Factor -
Article: The biophysical mechanisms of altered hyaluronan concentration in synovial fluid after anterior cruciate ligament transection.
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ABSTRACT: OBJECTIVES: The residence time of hyaluronan (HA) in the synovial fluid (SF) of knee joints was investigated using the rabbit anterior cruciate ligament transection (ACLT) model. The aims were to assess at 7 and 28 days after surgery for non-operated (NonOp), ACLT, and SHAM groups: 1) HA molecular mass (M(r) ) distribution in SF, 2) endogenous replenishment of HA after saline washout, 3) HA residence times in SF, and 4) synovium and subsynovium cellularity. METHODS: Adult NZW rabbits underwent ACLT or SHAM surgeries on one hind limb, while each contralateral limb was a NonOp control. At 7 or 28d after surgery, joints were aspirated for SF, lavaged with saline, injected with saline or polydisperse HA, and sampled over 8hrs. Fluid samples were analyzed for HA concentration and M(r) distribution to calculate HA residence times. RESULTS: HA M(r) -distributions showed 1) loss of high-M(r) HA at day 7, and a shift towards a lower-M(r) HA distribution at day 28, 2) endogenous replenishment of high-M(r) HA after washout, and 3) M(r) -dependent HA loss, particularly at day 7 after ACLT. The residence time of HA decreased with M(r) (∼27hrs for 7000-2500kDa to ∼7hrs for 250-50kDa) and at day 7 after ACLT (∼70% decrease). The subsynovium of ACLT joints contained 4) increased cellularity and neovascularization at 7 and 28 days. CONCLUSIONS: The residence time of HA in SF is transiently decreased after ACLT, suggesting a biophysical transport mechanism for the altered SF composition post-injury or during inflammation. © 2012 American College of Rheumatology.Arthritis & Rheumatism 08/2012; · 7.87 Impact Factor
