Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309-0596, United States.
Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309-0596, United States.
ACS Appl Bio Mater. 2023 Jul 17;6(7):2677-2689. doi: 10.1021/acsabm.3c00082. Epub 2023 Jun 27.
Matrix metalloproteinase (MMP)-sensitive hydrogels are promising for cartilage tissue engineering due to cell-mediated control over hydrogel degradation. However, any variability in MMP, tissue inhibitors of matrix metalloproteinase (TIMP), and/or extracellular matrix (ECM) production among donors will impact neotissue formation in the hydrogels. The goal for this study was to investigate the impact of inter- and intra-donor variability on the hydrogel-to-tissue transition. Transforming growth factor β3 was tethered into the hydrogel to maintain the chondrogenic phenotype and support neocartilage production, allowing the use of chemically defined medium. Bovine chondrocytes were isolated from two donor groups, skeletally immature juvenile and skeletally mature adult donors (inter-donor variability) and three donors within each group (intra-donor group variability). While the hydrogel supported neocartilaginous growth by all donors, donor age impacted MMP, TIMP, and ECM synthesis rates. Of the MMPs and TIMPs studied, MMP-1 and TIMP-1 were the most abundantly produced by all donors. Adult chondrocytes secreted higher levels of MMPs, which was accompanied by higher production of TIMPs. Juvenile chondrocytes exhibited more rapid ECM growth. By day 29, juvenile chondrocytes had surpassed the gel-to-tissue transition. On the contrary, the adult donors had a percolated polymer network indicating that despite higher levels of MMPs the gel-to-transition had not yet been achieved. The intra-donor group variability of MMP, TIMP, and ECM production was higher in adult chondrocytes but did not impact the extent of the gel-to-tissue transition. In summary, age-dependent inter-donor variations in MMPs and TIMPs significantly impact the timing of the gel-to-tissue transition in MMP-sensitive hydrogels.
基质金属蛋白酶（MMP）敏感水凝胶在软骨组织工程中很有前景，因为细胞可以控制水凝胶的降解。然而，供体之间 MMP、基质金属蛋白酶抑制剂（TIMP）和/或细胞外基质（ECM）产生的任何可变性都会影响水凝胶中新组织的形成。本研究的目的是研究供体间和供体内变异性对水凝胶向组织转变的影响。转化生长因子β3被固定在水凝胶中，以维持软骨细胞表型并支持新软骨的产生，从而可以使用化学定义的培养基。从两个供体组（骨骼未成熟的青少年和骨骼成熟的成年供体，即供体间变异性）和每个组内的三个供体（供体内变异性）中分离出牛软骨细胞。虽然所有供体的水凝胶都支持新的软骨生长，但供体年龄影响 MMP、TIMP 和 ECM 合成率。在所研究的 MMP 和 TIMP 中，MMP-1 和 TIMP-1 是所有供体中含量最高的。成年软骨细胞分泌的 MMP 水平较高，同时 TIMP 的产生也较高。青少年软骨细胞表现出更快的 ECM 生长。到第 29 天，青少年软骨细胞已经超过了凝胶到组织的转变。相反，成年供体的聚合物网络已经渗透，这表明尽管 MMP 水平较高，但凝胶到转变尚未完成。成年软骨细胞中 MMP、TIMP 和 ECM 产生的供体内变异性较高，但对凝胶到组织转变的程度没有影响。总之，MMP 和 TIMP 的年龄相关供体间差异显著影响 MMP 敏感水凝胶中凝胶到组织转变的时间。
