Zhang Kunxi, Song Li, Wang Jia, Yan Shifeng, Li Guifei, Cui Lei, Yin Jingbo
Department of Polymer Materials, Shanghai University, 99 Shangda Road, Shanghai 200444, PR China.
Medical Science & Research Center, Beijing Shijitan Hospital, Capital Medical University, 10 Tieyi Road, Beijing 100038, PR China.
Acta Biomater. 2017 Mar 15;51:246-257. doi: 10.1016/j.actbio.2017.01.043. Epub 2017 Jan 16.
Vascularization is of great importance to adipose tissue regeneration. Here we introduced a paradigm that using scaffold to induce ASC spheroids, so to promote vascularized adipose tissue regeneration. Poly (l-glutamic acid) (PLGA) was activated by EDC, followed by being cross-linked by Adipic dihydrazide (ADH) to form a homogeneous hydrogel. Lyophilization was then carried out to create porous structure. The PLGA hydrogel scaffold possessed a significant swollen hydrophilic network to weaken cell-scaffold adhesion but drive ASCs to aggregate to form spheroids. Increase of seeding cell density was proved to result in the increase of spheroid size, upregulating angiogenic genes (VEGF and FGF-2) expression by enhancing the hypoxia-induced paracrine secretion. Also, the adipogenic differentiation of ASCs was achieved in spheroids in vitro. Moreover, the in vivo vascularized adipose tissue regeneration was evaluated in the dorsum of nude mice. After 12weeks post-implantation, the significant angiogenesis was found in both adipogenic induced and non-induced engineered tissue. In adipogenic induced group, the clear ring-like morphology, the large vacuole in the middle of the cell and the Oil red O staining demonstrated adipose tissue formation.
Vascularization is of great importance to adipose tissue regeneration. Adipose derived stem cell (ASC) spheroids possessed not only the high efficiency of vascularization, but also the improved differentiation ability. Several research works have illustrated the advantage of ASC spheroids in vascularization. However, in adipose regeneration, ASC spheroid was rarely used. Even so, it is reasonable to believe that ASC spheroids hold a great promise in vascularized adipose tissue engineering. Thus in the present study, we introduced a method to create lots of ASC spheroids that acted as lots of individual adipogenesis and angiogenesis units inside of a porous hydrogel scaffold. Then, the scaffold carrying ASC spheroids was implanted subcutaneously in nude mice to preliminarily evaluate the adipose tissue generation and blood vessel formation.
血管化对脂肪组织再生非常重要。在此，我们引入了一种范式，即使用支架诱导脂肪干细胞球，从而促进血管化脂肪组织再生。聚（L-谷氨酸）（PLGA）由1-乙基-3-（3-二甲基氨基丙基）碳二亚胺（EDC）活化，随后通过己二酸二酰肼（ADH）交联形成均匀水凝胶。然后进行冻干以形成多孔结构。PLGA水凝胶支架具有显著肿胀的亲水性网络，可减弱细胞与支架的粘附，但促使脂肪干细胞聚集形成球状体。已证明接种细胞密度的增加会导致球状体尺寸增大，通过增强缺氧诱导的旁分泌分泌上调血管生成基因（血管内皮生长因子和碱性成纤维细胞生长因子-2）的表达。此外，脂肪干细胞在体外的球状体中实现了成脂分化。此外，在裸鼠背部评估了体内血管化脂肪组织的再生。植入后12周，在成脂诱导和未诱导的工程组织中均发现了显著的血管生成。在成脂诱导组中，清晰的环状形态、细胞中部的大液泡以及油红O染色表明有脂肪组织形成。
血管化对脂肪组织再生非常重要。脂肪来源干细胞（ASC）球状体不仅具有高效的血管化能力，而且具有改善的分化能力。多项研究工作已阐明了ASC球状体在血管化方面的优势。然而，在脂肪再生中，ASC球状体很少被使用。即便如此，有理由相信ASC球状体在血管化脂肪组织工程中具有巨大潜力。因此，在本研究中，我们引入了一种方法来创建大量的ASC球状体，这些球状体在多孔水凝胶支架内充当许多单独的成脂和血管生成单元。然后，将携带ASC球状体的支架皮下植入裸鼠体内，以初步评估脂肪组织生成和血管形成情况。
