Barbetta Andrea, Massimi Mara, Di Rosario Biancalucia, Nardecchia Stefania, De Colli Marianna, Devirgiliis Laura Conti, Dentini Mariella
Department of Chemistry, University of Rome La Sapienza, P.le A. Moro, 5, 00185 Rome, Italy.
Biomacromolecules. 2008 Oct;9(10):2844-56. doi: 10.1021/bm800599d. Epub 2008 Sep 26.
Gelatin is one of the most commonly used biopolymer for creating cellular scaffolds due to its innocuous nature. To create stable gelatin scaffolds at physiological temperature (37 degrees C), chemical cross-linking is a necessary step. In a previous paper (Biomacromolecules 2006, 7, 3059-3068), cross-linking was carried out by either radical polymerization of the methacrylated derivative of gelatin (GMA) or through the formation of isopeptide bonds catalyzed by transglutaminase. The method of scaffold production was based on emulsion templating in which an organic phase is dispersed in the form of discrete droplets into a continuous aqueous solution of the biopolymer. Both kinds of scaffolds were tested as culture medium for hepatocytes. It turned out that the enzymatic cross-linked scaffold performed superiorily in this respect, even though it was mechanically less stable than the GMA scaffold. In the present paper, in an attempt to improve the biocompatibility of the GMA-based scaffold, biopolymers present in the extracellular matrix (ECM) were included in scaffold formulation, namely, chondroitin sulfate and hyaluronic acid. These biopolymers were derivatized with methacrylic moieties to undergo radical polymerization together with GMA. The morphology of the scaffolds was tuned to some extent by varying the volume fraction of the internal phase and to a larger extent by inducing a controlled destabilization of the precursor emulsion through the use of additives. In this way, scaffolds with 44% of the void volume attributable to voids with a diameter exceeding 60 microm and with 79% of the interconnect area attributable to interconnects with a diameter exceeding 20 microm in diameter could be successfully synthesized. To test whether the inclusion of ECM components into scaffold formulation resolves in an improvement of their biocompatibility with respect to GMA scaffolds, hepatocytes were seeded on both kinds of scaffolds and cell viability and function assays were carried out and compared.
由于明胶性质无害，它是用于制造细胞支架最常用的生物聚合物之一。为了在生理温度（37摄氏度）下制造稳定的明胶支架，化学交联是必要步骤。在之前的一篇论文（《生物大分子》2006年，第7卷，3059 - 3068页）中，交联是通过明胶甲基丙烯酸酯衍生物（GMA）的自由基聚合或者通过转谷氨酰胺酶催化形成异肽键来进行的。支架生产方法基于乳液模板法，即有机相以离散液滴的形式分散到生物聚合物的连续水溶液中。两种支架都作为肝细胞的培养基进行了测试。结果表明，酶交联支架在这方面表现更优，尽管其机械稳定性不如GMA支架。在本文中，为了提高基于GMA的支架的生物相容性，细胞外基质（ECM）中存在的生物聚合物被纳入支架配方，即硫酸软骨素和透明质酸。这些生物聚合物用甲基丙烯酸部分进行衍生化，以便与GMA一起进行自由基聚合。通过改变内相的体积分数在一定程度上调整了支架的形态，并且通过使用添加剂诱导前驱体乳液的可控失稳在更大程度上进行了调整。通过这种方式，可以成功合成孔隙率为44%且孔隙直径超过60微米、互连面积为79%且互连直径超过20微米的支架。为了测试将ECM成分纳入支架配方是否能改善其相对于GMA支架的生物相容性，将肝细胞接种在两种支架上，并进行细胞活力和功能测定并比较。
