Collagen-containing scaffolds enhance attachment and proliferation of non-cultured bone marrow multipotential stromal cells

Large bone defects are ideally treated with autografts, which have many limitations. Therefore, osteoconductive scaffolds loaded with autologous bone marrow (BM) aspirate are increasingly used as alternatives. The purpose of this study was to compare the growth of multipotential stromal cells (MSCs) from unprocessed BM on a collagen-containing bovine bone scaffold (Orthoss® Collagen) with a non-collagen-containing bovine bone scaffold, Orthoss®. Another collagen-containing synthetic scaffold, Vitoss® was included in the comparison. Colonization of scaffolds by BM MSCs (n = 23 donors) was evaluated using microscopy, colony forming unit-fibroblast assay and flow-cytometry. The number of BM MSCs initially attached to Orthoss® Collagen and Vitoss® was similar but greater than Orthoss® (p = 0.001 and p = 0.041, respectively). Furthermore, the number of MSCs released from Orthoss® Collagen and Vitoss® after 2-week culture was also higher compared to Orthoss® (p = 0.010 and p = 0.023, respectively). Interestingly, collagen-containing scaffolds accommodated larger numbers of lymphocytic and myelomonocytic cells. Additionally, the proliferation of culture-expanded MSCs on Orthoss® collagen and Vitoss® was greater compared to Orthoss® (p = 0.047 and p = 0.004, respectively). Collectively, collagen-containing scaffolds were superior in supporting the attachment and proliferation of MSCs when they were loaded with unprocessed BM aspirates. This highlights the benefit of collagen incorporation into bone scaffolds for use with autologous bone marrow aspirates as autograft substitutes.