Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
J Tissue Eng Regen Med. 2011 Oct;5(9):712-21. doi: 10.1002/term.370. Epub 2010 Dec 30.
Cell sources and tissue integration between cartilage and bone regions are critical to successful osteochondral regeneration. In this study, human umbilical cord mesenchymal stromal cells (hUCMSCs), derived from Wharton's jelly, were introduced to the field of osteochondral tissue engineering and a new strategy for osteochondral integration was developed by sandwiching a layer of cells between chondrogenic and osteogenic constructs before suturing them together. Specifically, hUCMSCs were cultured in biodegradable poly-L-lactic acid scaffolds for 3 weeks in either chondrogenic or osteogenic medium to differentiate cells toward cartilage or bone lineages, respectively. A highly concentrated cell solution containing undifferentiated hUCMSCs was pasted onto the surface of the bone layer at week 3 and the two layers were then sutured together to form an osteochondral composite for another 3 week culture period. Chondrogenic and osteogenic differentiation was initiated during the first 3 weeks, as evidenced by the expression of type II collagen and runt-related transcription factor 2 genes, respectively, and continued with the increase of extracellular matrix during the last 3 weeks. Histological and immunohistochemical staining, such as for glycosaminoglycans, type I collagen and calcium, revealed better integration and transition of these matrices between two layers in the composite group containing sandwiched cells compared to other control composites. These results suggest that hUCMSCs may be a suitable cell source for osteochondral regeneration, and the strategy of sandwiching cells between two layers may facilitate scaffold and tissue integration.
软骨和骨区域之间的细胞来源和组织整合对于成功的骨软骨再生至关重要。在这项研究中，人脐带间充质基质细胞（hUCMSCs）来源于华通氏胶，被引入到骨软骨组织工程领域，并开发了一种新的骨软骨整合策略，即在将软骨和骨构建体缝合在一起之前，在它们之间夹一层细胞。具体来说，hUCMSCs 在可生物降解的聚-L-乳酸支架中培养 3 周，分别在软骨形成或成骨培养基中培养，以使细胞向软骨或骨谱系分化。在第 3 周，将含有未分化的 hUCMSCs 的高浓度细胞溶液粘贴到骨层的表面，然后将两层缝合在一起，再进行 3 周的培养。在最初的 3 周内，启动了软骨和成骨分化，分别表现为 II 型胶原和 runt 相关转录因子 2 基因的表达，并且在最后 3 周内随着细胞外基质的增加而继续进行。组织学和免疫组织化学染色，如糖胺聚糖、I 型胶原和钙，显示在含有夹杂物的复合组中，与其他对照复合组相比，这些基质在两层之间的整合和过渡更好。这些结果表明，hUCMSCs 可能是骨软骨再生的合适细胞来源，并且在两层之间夹细胞的策略可能有助于支架和组织整合。
