Cartilage defects have a limited ability to self-heal. Stem cell treatment is a promising approach; however, replicative senescence is a challenge to acquiring large-quantity and high-quality stem cells for cartilage regeneration. Synovium-derived stem cells (SDSCs) are a tissue-specific stem cell for cartilage regeneration. Our recent findings suggest that decellularized stem cell matrix (DSCM) can rejuvenate expanded SDSCs in cell proliferation and chondrogenic potential. In this study, we were investigating (1) whether transforming growth factor (TGF)-β1 and TGF-β3 played a similar role in chondrogenic induction of SDSCs after expansion on either DSCM or plastic flasks (plastic), and (2) whether DSCM-expanded SDSCs had an enhanced capacity in repairing partial-thickness cartilage defects in a minipig model. SDSCs were isolated from synovium in two 3-month-old pigs and DSCM was prepared using SDSCs. Passage 2 SDSCs were expanded on either DSCM or plastic for one passage. The expanded cells were evaluated for cell morphology, chondrogenic capacity, and related mechanisms. TGF-β1 and TGF-β3 were compared for their role in chondrogenesis of SDSCs after expansion on either DSCM or plastic. The chondrogenic induction medium without TGF-β served as a control. In 13 minipigs, we intraarticularly injected DSCM- or plastic-expanded SDSCs or saline into knee partial-thickness cartilage defects and assessed their repair using histology and immunohistochemistry. We found DSCM-expanded SDSCs were small, had a fibroblast-like shape, and grew quickly in a three-dimensional format with concomitant up-regulation of phosphocyclin D1 and TGF-β receptor II. Plastic-expanded SDSCs exhibited higher mRNA levels of chondrogenic markers when incubated with TGF-β3, while DSCM-expanded SDSCs displayed comparable chondrogenic potential when treated with either TGF-β isotype. In the minipig model, DSCM-expanded SDSCs were better than plastic-expanded SDSCs in enhancing collagen II and sulfated glycosaminoglycan expression in repair of partial-thickness cartilage defects, but both groups were superior to the saline control group. Our observations suggested that DSCM is a promising cell expansion system that can promote cell proliferation and enhance expanded cell chondrogenic potential in vitro and in vivo. Our approach could lead to a tissue-specific cell expansion system providing large-quantity and high-quality stem cells for the treatment of cartilage defects.
Platelet-rich-plasma (PRP) has attracted great attention and has been increasingly used for a variety of clinical applications including orthopaedic surgeries, periodontal and oral surgeries, maxillofacial surgeries, plastic surgeries, and sports medicine. However, very little is known about the antimicrobial activities of PRP. In this study, PRP is found to have antimicrobial properties both in vitro and in vivo. In vitro, the antimicrobial properties of PRP have been found to be bacterial strain specific and time specific: PRP has significantly (80–100 fold reduction in colony forming units) inhibited the growth of methicillin sensitive and methicillin resistant Staphylococcus aureus, Group A streptococcus, and Neisseria gonorrhoeae within the first few hours but it has no significant antimicrobial properties against E. coli and Pseudomonas. The antimicrobial properties of PRP also depend on the concentration of thrombin. In vivo, an implant-associated spinal infection rabbit model has been established and used to evaluate the antimicrobial and wound healing properties of PRP. Compared to the infection controls, PRP treatment has resulted in significant reduction in bacterial colonies in bone samples at all time points studied (i.e. 1, 2, and 3 weeks) and significant increase in mineralized tissues (thereby better bone healing) at post-operative weeks 2 and 3. PRP therefore may be a useful adjunct strategy against post-operative implant-associated infections.
Level I, prospective randomized trial.
The purpose of this study was to determine the minimum number of throws needed for knot security for square knots using 5 common suture materials and 3 common sizes by in vitro single load to failure biomechanical testing. The hypothesis was that each suture combination studied would share a common minimum of at least 5 throws to guarantee security. Five suture materials (FiberWire [Arthrex, Inc, Naples, Florida], Monosof, Surgipro, Maxon, and Polysorb [Covidien, Mansfield, Massachusetts]) with varying suture sizes (#5, #2, 0, 2-0, and 4-0) were tied in vitro, varying the number of square knot throws (3, 4, 5, and 6). Twenty knots for each combination were statically loaded to failure in tension; whether the knot failed by fracture or slippage and the tensile strength at knot failure was determined. For the tested materials, at least 5 flat square throws should be used to confer knot security based on a binomial proportion score 95% confidence interval (CI) 0.84 to 1.0 or at least 4 throws for a 95% CI of 0.76 to 0.99. FiberWire requires 6 flat square throws per knot for security at either 95% CI level. Unless a surgeon has specific knowledge of experimental evidence that fewer throws are necessary for a specific application, the default should be a minimum of 4 throws, with 5 conferring additional security in most situations, and FiberWire requiring 6 throws.
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