2017 ISAKOS Biennial Congress ePoster #1316
In Vitro Repair of Meniscus Radial Tear Using Hydrogels Seeded with Adipose-Derived Stem Cells And TGF-ß3
Hiroshi Sasaki, MD, PhD, Kobe JAPAN
Ben Rothrauff, MD, PhD, Pittsburgh, PA UNITED STATES
Peter G. Alexander, PhD, Pittsburgh, PA UNITED STATES
Riccardo Gottardi, PhD, Pittsburgh, PA UNITED STATES
Hang Lin, PhD, Pittsburgh, PA UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES
Rocky S. Tuan, PhD, Pittsburgh, PA UNITED STATES
University of Pittsburgh, Pittsburgh, PA, UNITED STATES
FDA Status Not Applicable
The injection of ASC-seeded hydrogels with trapped TGF-ß3 into the wound site as an augmentation to suture repair may be an effective technique used to repair meniscus radial tears in order to prevent the development of osteoarthritis in the damaged knee
INTRODUCTION; Radial tears of the meniscus represent the common injury. To date, there are no established, effective treatments for radial meniscal tears. It has been reported that adipose-derived stem cells (ASC) can form meniscal fibrocartilage in the avascular zones. ASCs are an attractive cell type for tissue regeneration because they can be isolated quickly in greater numbers than other stem cells. TGF-ß induced ASC chondrogenesis is well established in vitro. However, the use of ASC for meniscus repair is unexplored. The purpose of this study is to assess fibrocartilage development in a ASC-seeded hydrogel with TGF-ß3 as a potential surgical method to enhance meniscal repair for radial tears.
METHODS; Visible light photo-crosslinkable hydrogels comprised of 10% methacrylated gelatin (mGL) were prepared. Human ASC were isolated from the infrapatellar fat pad (IPFP) after TKA under IRB. Radial tear models were adapted from Kazunori Shimomura et al. Adult bovine menisci were harvested within 24hr of slaughter. Cylinder-shaped explants (5mm diameter x 10mm height) were then excised from the inner avascular region using a biopsy punch. A radial tear was modeled by cutting the explant to half its depth in a manner perpendicular to the meniscal main fibers. The ASC-seeded hydrogels were injected into the defect site, photocrosslinked. Six conditions were tested including defect repair using ASC-seeded or acellular hydrogels with trapped TGF-ß3 (2µg/ml) in the hydrogel, soluble TGF-ß3 (10ng/ml) in the medium or in the absence of TGF-ß3. Samples were cultured for 4 or 8 weeks and tested for mechanical strength or histological analysis. Each study was carried out in triplicate. Significant differences among different groups were determined by two-tailed Student’s t-test for two-group comparisons or ANOVA for multiple-group comparisons. The data were analyzed with SPSS 21.0 and significance was considered at p < 0.05.
RESULTS; Matrix staining with Picrosirius red showed that ASC-seeded hydrogels promote greater meniscus healing as compared to acellular hydrogel and that trapped TGF-ß3 in the hydrogel or soluble TGF-ß3 in the medium improved collagen deposition and healing of radial tears compared to the TGF-ß3 negative group. Similarly, ASC and TGF-ß3 alone or in combination improved the mechanical properties (Young’s modulus and load to failure) of the repaired meniscus explants at 4 and 8 weeks. While no significant difference was observed between the effect of trapped TGF-ß3 and soluble TGF-ß3 in the medium, TGF-ß3 greatly enhanced repair of the meniscus explants over TGF-?3-free controls. Immunohistochemical analysis of the torn site showed strong staining for collagen type I at the margins of the radial tear in each group. On the other hand, collagen type II was detected only in ASC-seeded groups with trapped TGF-ß3 and ASC-seeded hydrogels with soluble TGF-ß3.
DISCUSSION; This study demonstrates that ASC in a hydrogel can promote healing and mechanical properties of meniscus explants torn to model radial tears through the avascular zone. TGF-ß3 either trapped within the hydrogel or supplied in the growth medium accelerate chondrogenic differentiation of ASCs. By using ASCs isolated from IPFP, it may be possible to repair meniscal radial tears in a single operation at a single operative site.