Evaluation of equine synovial-derived extracellular matrix scaffolds seeded with equine synovial-derived mesenchymal stem cells.

OBJECTIVE To create a bioactive synovium scaffold by infusing decellularized synovial-derived extracellular matrix (synECM) with synovial-derived mesenchymal stem cells (synMSCs). SAMPLE Synovium from the femoropatellar and medial femorotibial joints of equine cadavers. PROCEDURES The synMSCs were cultured in monolayer and not treated or cotransduced to enhance expression of green fluorescent protein (GFP) and human bone morphogenetic protein (BMP)-2. The synECM was decellularized with 0.1% peracetic acid and then seeded with synMSCs (0.5 × 106 cells/0.5 mL) by use of a 30% serum gradient. Samples were evaluated on days 0, 3, 7, and 14. Cell migration, differentiation, and distribution into the synECMs were determined by cell surface marker CD90, viability, histologic morphology, and fluorescence microscopy results and expression of GFP, BMP-2, hyaluronan (HA), and proteoglycan (PG). RESULTS At day 14, synMSCs were viable and had multiplied 2.5-fold in the synECMs. The synECMs seeded with synMSCs had a significant decrease in CD90 expression and significant increases in HA and PG expression. The synECMs seeded with synMSCs cotransduced with GFP, or BMP-2 had a significant increase in BMP-2 expression. CONCLUSIONS AND CLINICAL RELEVANCE The synECM seeded with synMSCs or synMSCs cotransduced with GFP, or BMP-2 yielded a bioactive synovial scaffold. Expression of BMP-2 by synMSCs cotransduced to enhance expression of BMP-2 or GFP and an accompanying increase in both HA and PG expression indicated production of anabolic agents and synoviocyte differentiation in the scaffold. Because BMP-2 can promote repair of damaged cartilage, such a bioactive scaffold could be useful for treatment of injured cartilage.

Comparison of four methods for generating decellularized equine synovial extracellular matrix.

OBJECTIVE To evaluate 4 methods for generating decellularized equine synovial extracellular matrix. SAMPLE Villous synovium harvested from the femoropatellar and medial femorotibial joints of 4 healthy adult horses < 7 years of age. Synovial samples were frozen (-80°C) until used. PROCEDURES Synovial samples were thawed and left untreated (control) or decellularized with 1 of 4 methods (15 samples/horse/method): incubation in 0.1% peracetic acid (PAA), incubation in 0.1% PAA twice, incubation in 1% Triton X-100 followed by incubation in DNase, and incubation in 2M NaCl followed by incubation in DNase. Control and decellularized samples were examined for residual cells, villous integrity, and collagen structure and integrity by means of histologic examination and scanning electron microscopy; cell viability was evaluated by means of culture and exclusion staining. Decellularization efficiency was assessed by testing for DNA content and DNA fragment size. RESULTS Incubation in PAA once preserved the synovial villous architecture, but resulted in high DNA content and retention of large (> 25,000 base pair) DNA fragments. Incubation in Triton and incubation in NaCl resulted in low DNA content and short (< 200 base pair) DNA fragments, but destroyed the synovial villous architecture. Incubation in PAA twice resulted in low DNA content and short DNA fragments while retaining the synovial villous architecture. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that of the methods evaluated, incubation in 0.1% PAA twice was the best method for generating decellularized equine synovial extracellular matrix.