Although previous studies have established alginate as a three-dimensional scaffold for chondrogenic differentiation of mesenchymal stem cells (MSCs), little is known about the cytotoxic effects of the polymerizing and chelating reagents used in the alginate recovered cellular method. Swine MSCs (sMSC) were suspended in the polymerizing agent, CaCl(2), and viability was assessed using a trypan blue exclusion assay at intervals over 2 h. MSCs were also suspended in two different chelating agents, 55 mM sodium citrate and 50 mM EDTA, and viability was calculated. Finally, sMSCs and human MSCs were encapsulated and cultured in vitro. The sMSC were collected at day 4 and the cells were recovered by chelation. Encapsulated hMSCs were cultured with TGFβ3 and IGF-1 and assayed by qRT-PCR for collagen types I and II and sox9 with encapsulated human dermal fibroblasts and chondrocytes as controls recovered on days 0, 7, and 14. Only 53% of sMSCs were viable after 10 min in CaCl(2), the standard polymerization period, whereas 94% of encapsulated sMSCs in polymerized alginate were alive at 15 days. After 20 min in chelating agents, sodium citrate and EDTA, only 46% and 17% of the cells, were viable, respectively. The alginate recovered sMSCs yielded 12% survival. Human MSCs upregulated cartilage-specific collagen type II over the 14-day culture. Collagen I remained unchanged in the hMSCs. Alginate is a suitable agent for chondrodifferentiation of MSCs and can be dissolved by chelation, but the agents involved in hydrogel polymerization and cell recovery should be altered to improve MSC survival.

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Surgical treatment of thumb basal joint arthritis is aimed at pain relief, restoration of pinch strength, and stability. We describe a variation of the abductor pollicus longus (APL) suspension arthroplasty originally described by Thompson, which maximizes strength of repair and is technically simple to perform. The technique consists of a trapeziectomy followed by resection of a slip of the APL and secure docking of the tendon into the base of the index metacarpal base. Stability is enhanced with a 3.0 mm biotenodesis screw. From March 2009 to September 2011, 50 patients were treated at our institution. Early results showed consistent pain relief, functional improvement, and minimal complications. The data support APL suspension arthroplasty with tenodesis screw fixation as a safe and effective treatment for CMC arthritis.