Jaklenec Ana, Hinckfuss Alexandra, Bilgen Bahar, Ciombor Deborah M, Aaron Roy, Mathiowitz Edith
Center for Biomedical Engineering, Brown University, Providence, RI 02912, USA.
Biomaterials. 2008 Apr;29(10):1518-25. doi: 10.1016/j.biomaterials.2007.12.004. Epub 2007 Dec 31.
Growth factors have become an important component for tissue engineering and regenerative medicine. Insulin-like growth factor-I (IGF-I) and transforming growth factor-beta1 (TGF-beta 1) in particular have great significance in cartilage tissue engineering. Here, we describe sequential release of IGF-I and TGF-beta 1 from modular designed poly(l,d-lactic-co-glycolic acid) (PLGA) scaffolds. Growth factors were encapsulated in PLGA microspheres using spontaneous emulsion, and in vitro release kinetics was characterized by ELISA. Incorporating BSA in the IGF-I formulations decreased the initial burst from 80% to 20%, while using uncapped PLGA rather than capped decreased the initial burst of TGF-beta 1 from 60% to 0% upon hydration. The bioactivity of released IGF-I and TGF-beta 1 was determined using MCF-7 proliferation assay and HT-2 inhibition assay, respectively. Both growth factors were released for up to 70 days in bioactive form. Scaffolds were fabricated by fusing bioactive IGF-I and TGF-beta 1 microspheres with dichloromethane vapor. Three scaffolds with tailored release kinetics were fabricated: IGF-I and TGF-beta 1 released continuously, TGF-beta 1 with IGF-I released sequentially after 10 days, and IGF-I with TGF-beta 1 released sequentially after 7 days. Scaffold swelling and degradation were characterized, indicating a peak swelling ratio of 4 after 7 days of incubation and showing 50% mass loss after 28 days, both consistent with scaffold release kinetics. The ability of these scaffolds to release IGF-I and TGF-beta 1 sequentially makes them very useful for cartilage tissue engineering applications.
生长因子已成为组织工程和再生医学的重要组成部分。特别是胰岛素样生长因子-I（IGF-I）和转化生长因子-β1（TGF-β1）在软骨组织工程中具有重要意义。在此，我们描述了模块化设计的聚（l，d-乳酸-共-乙醇酸）（PLGA）支架对IGF-I和TGF-β1的顺序释放。使用自发乳化法将生长因子包裹在PLGA微球中，并通过酶联免疫吸附测定法（ELISA）表征体外释放动力学。在IGF-I制剂中加入牛血清白蛋白（BSA）可将初始突释从80%降至20%，而使用未封端的PLGA而非封端的PLGA可使水合后TGF-β1的初始突释从60%降至0%。分别使用MCF-7增殖试验和HT-2抑制试验测定释放的IGF-I和TGF-β1的生物活性。两种生长因子均以生物活性形式释放长达70天。通过用二氯甲烷蒸汽融合生物活性IGF-I和TGF-β1微球制备支架。制备了三种具有定制释放动力学的支架：IGF-I和TGF-β1持续释放、TGF-β1在10天后与IGF-I顺序释放、IGF-I在7天后与TGF-β1顺序释放。对支架的肿胀和降解进行了表征，结果表明孵育7天后的峰值肿胀率为4，28天后质量损失50%，均与支架释放动力学一致。这些支架顺序释放IGF-I和TGF-β1的能力使其在软骨组织工程应用中非常有用。
