Cellular encapsulation in 3D hydrogels for tissue engineering.
Cellular encapsulation in 3D hydrogels for tissue engineering.
复制标题
DOI：
10.3791/1590
复制
发表时间：
2009-10-26
期刊：
影响因子：
--
通讯作者：
Burdick, Jason
中科院分区：
文献类型：
--
作者：
Khetan, Sudhir;Burdick, Jason
将细胞三维包封在水凝胶内是一种日益重要且流行的细胞培养技术，对于组织工程构建体的开发也具有重要意义。与标准组织培养相比，由于这种环境具有类似组织的特性和三维结构，它能更好地模拟细胞在体内的环境。合成聚合物水凝胶是水溶胀的网络，可以设计为稳定的，或者当包封的细胞沉积新组织时，通过水解或蛋白水解而降解。人们已经对多种聚合物进行了此类应用的探索，例如聚乙二醇和透明质酸。最常见的是，聚合物通过甲基丙烯酸酯或丙烯酸酯等反应性基团进行官能化，这些基团能够通过各种机制发生交联。在过去的十年中，在构建这些微环境方面取得了很大进展——例如，通过物理或悬垂共价结合生化信号——以提高细胞活力并引导细胞表型，包括包封干细胞的分化（伯迪克等人）。我们实验室和其他实验室已经对以下细胞三维包封方法进行了优化，以最大限度地提高细胞相容性并尽量减少水凝胶处理步骤。在以下实验方案中（操作过程见图1），假定能够发生交联的官能化聚合物已经准备好；有关应用于组织工程领域的聚合物化学的优秀综述可在其他地方找到（伯迪克等人），并且这些方法适用于多种聚合物类型。此外，此处重点介绍的迈克尔型加成（见卢托夫等人）和光引发自由基（见埃利斯西夫等人）机制只是已报道的交联技术中的一小部分。混合模式交联是另一种常用且有效的引导包封细胞表型的模式，在这种模式中，一部分反应性基团首先通过加成交联被消耗，然后通过自由基机制进行交联（赫坦等人，萨利纳斯等人）。
The 3D encapsulation of cells within hydrogels represents an increasingly important and popular technique for culturing cells and towards the development of constructs for tissue engineering. This environment better mimics what cells observe in vivo, compared to standard tissue culture, due to the tissue-like properties and 3D environment. Synthetic polymeric hydrogels are water-swollen networks that can be designed to be stable or to degrade through hydrolysis or proteolysis as new tissue is deposited by encapsulated cells. A wide variety of polymers have been explored for these applications, such as poly(ethylene glycol) and hyaluronic acid. Most commonly, the polymer is functionalized with reactive groups such as methacrylates or acrylates capable of undergoing crosslinking through various mechanisms. In the past decade, much progress has been made in engineering these microenvironments - e.g., via the physical or pendant covalent incorporation of biochemical cues - to improve viability and direct cellular phenotype, including the differentiation of encapsulated stem cells (Burdick et al.). The following methods for the 3D encapsulation of cells have been optimized in our and other laboratories to maximize cytocompatibility and minimize the number of hydrogel processing steps. In the following protocols (see Figure 1 for an illustration of the procedure), it is assumed that functionalized polymers capable of undergoing crosslinking are already in hand; excellent reviews of polymer chemistry as applied to the field of tissue engineering may be found elsewhere (Burdick et al.) and these methods are compatible with a range of polymer types. Further, the Michael-type addition (see Lutolf et al.) and light-initiated free radical (see Elisseeff et al.) mechanisms focused on here constitute only a small portion of the reported crosslinking techniques. Mixed mode crosslinking, in which a portion of reactive groups is first consumed by addition crosslinking and followed by a radical mechanism, is another commonly used and powerful paradigm for directing the phenotype of encapsulated cells (Khetan et al., Salinas et al.).