| Summary: | Previous studies reported that matrix protein supplementation (fibronectin/fibrinogen, FN/FG) of agarose gel microcapsules enhances survival and pulmonary retention of syngeneic rat multipotent stromal cells (MSCs). I hypothesized that additional supplementation of microcapsules with osteopontin (OPN) and transglutaminase 2 (TG2) would enhance cell survival, while stabilizing the provisional matrix. Using monomeric OPN or OPN polymerized with TG2, I examined human MSC adhesion, morphology, focal contact formation and apoptosis. Polymeric OPN induced greater adhesion than monomeric OPN (84.5±10.7 vs. 44.3±10.0cells/field), and also significantly enhanced focal contact formation (351.5±21.2 vs. 45.6±17.6 focal contact sites/cell) and cell spreading (2.7x103±0.20x103μm2 vs. 1.2x103±0.26x102μm2) while preserving MSC pluripotency. Microcapsules supplemented with FN/FG, polymeric OPN and TG2 demonstrated significantly less apoptotic cells than FN/FG microcapsules (14.0±2.34% vs. 28.2±3.22%). Reduced apoptosis was attributed to matrix stabilization by TG2 and the synergistic activity of matrix proteins. It is anticipated that this enhanced survival will maximize the therapeutic potential of MSCs.
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