Salinas Chelsea N, Anseth Kristi S
Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309-0424, USA.
J Tissue Eng Regen Med. 2008 Jul;2(5):296-304. doi: 10.1002/term.95.
An investigation was undertaken into the method of delivery of RGD peptide motifs to adult human mesenchymal stem cells (hMSCs) encapsulated in poly(ethylene glycol) (PEG) hydrogel systems. Previous studies have shown that the viability of hMSCs encapsulated in bio-inert hydrogels, such as PEG-based gels, decreases over time. hMSCs are an adhesive-dependent cell type, requiring attachment sites to maintain their survival and function. The incorporation of tethered RGD peptide motifs was found to sustain a high level of hMSC survival in PEG gels. However, previous reports are largely limited to pendantly tethered RGD in gels; therefore, further investigation into hMSCs' affinity for and response to the contextual presentation of RGD was studied using varying methods of RGD attachment to the PEG gel, as well as delivery of soluble RGD peptides. Studies with encapsulated hMSCs showed that the constrained RGD peptide, bound via two links to the PEG gel, promoted approximately 60% cell survival, while tethering the RGD as a pendant group, bound via a single link to the PEG gel, promoted approximately 80% cell survival. Interestingly, incorporating a glycine spacer arm to the RGD pendant tether further enhanced survival to approximately 88%. Investigations with solubly delivered peptides resulted in a dramatic decrease in cell viability with time, eventually leading to survival that was similar to that of unmodified PEG gels. Integrin staining for alphavbeta3 and alpha4, as well as focal adhesion staining, correlates to the trends in hMSC survival for covalently-bound RGD motifs and a loss of viability for the solubly delivered peptide systems.
对将RGD肽基序递送至封装在聚乙二醇（PEG）水凝胶系统中的成人人间充质干细胞（hMSCs）的方法进行了研究。先前的研究表明，封装在生物惰性水凝胶（如基于PEG的凝胶）中的hMSCs的活力会随着时间的推移而降低。hMSCs是一种依赖黏附的细胞类型，需要附着位点来维持其存活和功能。发现引入连接的RGD肽基序可在PEG凝胶中维持高水平的hMSC存活。然而，先前的报道大多局限于凝胶中悬垂连接的RGD；因此，使用不同的RGD附着于PEG凝胶的方法以及可溶性RGD肽的递送，进一步研究了hMSCs对RGD的上下文呈现的亲和力和反应。对封装的hMSCs的研究表明，通过两个连接与PEG凝胶结合的受限RGD肽可促进约60%的细胞存活，而将RGD作为侧链基团通过单个连接与PEG凝胶结合时，可促进约80%的细胞存活。有趣的是，在RGD侧链连接中加入甘氨酸间隔臂可进一步将存活率提高至约88%。对可溶性递送肽的研究导致细胞活力随时间急剧下降，最终导致存活率与未修饰的PEG凝胶相似。αvβ3和α4的整合素染色以及粘着斑染色与共价结合的RGD基序的hMSC存活趋势以及可溶性递送肽系统的活力丧失相关。
