Chen Chu-Hsin, Xu Peng, Chen Yahong, Xue Ke, Liu Kai
Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine 639 Zhi Zao Ju Road, Shanghai 200011, People's Republic of China.
Am J Transl Res. 2021 Dec 15;13(12):13438-13451. eCollection 2021.
Flap prelamination has been successfully established in tissue engineering; however, cartilage generation through combination of an expanded flap and chondrocyte sheets has not been reported. Herein, we investigate the effect of tissue expansion on chondrocyte sheets in prelaminating an expanded chondrocutaneous flap. Chondrocyte sheets were implanted into a tissue expander capsule following which capsule inflation was performed weekly. At 4 and 12 weeks post implantation, the specimens were examined with histology and immunohistochemistry analyses. Extracellular matrix (ECM) formation and type II collagen deposition in the regenerated cartilage tissue were also examined. After 4 weeks of implantation, the generated cartilage was phenotypically stable with minimal hypertrophy, while that formed after the 12-week expansion showed visible hypertrophic differentiation. To evaluate the effect of static pressure and/or hypoxic conditions generated by the expanding tissue, static pressure and/or hypoxic conditions were reproduced . The chondrocyte sheets stimulated by mechanical static pressure and hypoxia maintained their chondrogenic phenotype. The expression of aggrecan, collagen II, Sox-9, and HIF-1α was increased in chondrocyte sheets cultured in 2% oxygen (hypoxia); however, aggrecan, collagen II, and Sox-9 were downregulated in the static pressure/normoxia group. These results suggest that the expanded environment promoted cartilage formation by the chondrocyte cell sheets, while mechanical forces and hypoxic conditions allowed chondrocyte cell sheets to retain their chondrogenic phenotype.
皮瓣预层压技术已在组织工程中成功建立；然而，通过扩张皮瓣与软骨细胞片结合生成软骨的情况尚未见报道。在此，我们研究组织扩张对预层压扩张软骨皮瓣中软骨细胞片的影响。将软骨细胞片植入组织扩张器囊内，随后每周进行囊内充气。在植入后4周和12周，对标本进行组织学和免疫组织化学分析。还检测了再生软骨组织中细胞外基质（ECM）的形成和II型胶原的沉积。植入4周后，生成的软骨表型稳定，肥大程度最小，而12周扩张后形成的软骨则出现明显的肥大分化。为评估扩张组织产生的静压力和/或缺氧条件的影响，重现了静压力和/或缺氧条件。受机械静压力和缺氧刺激的软骨细胞片维持其软骨生成表型。在2%氧气（缺氧）条件下培养的软骨细胞片中，聚集蛋白聚糖、II型胶原、Sox-9和HIF-1α的表达增加；然而，在静压力/常氧组中，聚集蛋白聚糖、II型胶原和Sox-9的表达下调。这些结果表明，扩张环境促进了软骨细胞片形成软骨，而机械力和缺氧条件使软骨细胞片保持其软骨生成表型。
