Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA; BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA.
Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA.
Acta Biomater. 2014 Aug;10(8):3409-20. doi: 10.1016/j.actbio.2014.04.013. Epub 2014 Apr 24.
Hydrolytically biodegradable poly(ethylene glycol) (PEG) hydrogels offer a promising platform for chondrocyte encapsulation and tuning degradation for cartilage tissue engineering, but offer no bioactive cues to encapsulated cells. This study tests the hypothesis that a semi-interpenetrating network of entrapped hyaluronic acid (HA), a bioactive molecule that binds cell surface receptors on chondrocytes, and crosslinked degradable PEG improves matrix synthesis by encapsulated chondrocytes. Degradation was achieved by incorporating oligo (lactic acid) segments into the crosslinks. The effects of HA molecular weight (MW) (2.9×10(4) and 2×10(6)Da) and concentration (0.5 and 5mgg(-1)) were investigated. Bovine chondrocytes were encapsulated in semi-interpenetrating networks and cultured for 4weeks. A steady release of HA was observed over the course of the study with 90% released by 4weeks. Incorporation of HA led to significantly higher cell numbers throughout the culture period. After 8days, HA increased collagen content per cell, increased aggrecan-positive cells, while decreasing the deposition of hypertrophic collagen X, but these effects were not sustained long term. Measuring total sulfated glycosaminoglycan (sGAG) and collagen content within the constructs and released to the culture medium after 4weeks revealed that total matrix synthesis was elevated by high concentrations of HA, indicating that HA stimulated matrix production although this matrix was not retained within the hydrogels. Matrix-degrading enzymes were elevated in the low-, but not the high-MW HA. Overall, incorporating high-MW HA into degrading hydrogels increased chondrocyte number and sGAG and collagen production, warranting further investigations to improve retention of newly synthesized matrix molecules.
水可降解的聚乙二醇（PEG）水凝胶为软骨细胞包封和调整降解提供了一个有前途的平台，用于软骨组织工程，但它不能为包封的细胞提供生物活性信号。本研究测试了以下假设：包埋的透明质酸（HA）（一种能与软骨细胞表面受体结合的生物活性分子）的半互穿网络与交联的可降解 PEG 一起，可以提高包封的软骨细胞的基质合成能力。通过将低聚（乳酸）片段掺入交联结构中来实现降解。研究了 HA 分子量（MW）（2.9×10（4）和 2×10（6）Da）和浓度（0.5 和 5mgg（-1））的影响。牛软骨细胞被包埋在半互穿网络中并培养 4 周。在整个研究过程中观察到 HA 的持续释放，4 周内释放了 90%。HA 的掺入导致整个培养期间细胞数量显著增加。8 天后，HA 增加了每细胞的胶原含量，增加了聚集蛋白阳性细胞，同时减少了肥大性胶原 X 的沉积，但这些效果并没有持续很长时间。测量构建物内的总硫酸化糖胺聚糖（sGAG）和胶原含量以及 4 周后释放到培养基中的含量，结果表明高浓度的 HA 可提高总基质合成，表明 HA 刺激了基质产生，尽管这种基质未保留在水凝胶中。在低分子量但不是高分子量的 HA 中，基质降解酶升高。总体而言，将高分子量 HA 掺入降解水凝胶中可以增加软骨细胞数量和 sGAG 和胶原的产生，值得进一步研究以提高新合成的基质分子的保留率。
