Cigan Alexander D, Nims Robert J, Vunjak-Novakovic Gordana, Hung Clark T, Ateshian Gerard A
Departments of Mechanical Engineering, Biomedical Engineering and Medicine, Columbia University, New York, NY 10027, United States.
Departments of Mechanical Engineering, Biomedical Engineering and Medicine, Columbia University, New York, NY 10027, United States.
J Biomech. 2016 Jul 5;49(10):2089-2094. doi: 10.1016/j.jbiomech.2016.05.020. Epub 2016 May 21.
Cartilage tissue engineering is a promising approach to treat osteoarthritis. However, current techniques produce tissues too small for clinical relevance. Increasingly close-packed channels have helped overcome nutrient transport limitations in centimeter-sized chondrocyte-agarose constructs, yet optimal channel spacings to recapitulate native cartilage compositional and mechanical properties in constructs this large have not been identified. Transient active TGF-β treatment consistently reproduces native compressive Young׳s modulus (EY) and glycosaminoglycan (GAG) content in constructs, but standard dosages of 10ng/mL exacerbate matrix heterogeneity. To ultimately produce articular layer-sized constructs, we must first optimize channel spacing and investigate the role of TGF-β in the utility of channels. We cultured ∅10mm constructs with 0, 12, 19, or 27 nutrient channels (∅1mm) for 6-8 weeks with 0, 1, or 10ng/mL TGF-β; subsequently we analyzed them mechanically, biochemically, and histologically. Constructs with 12 or 19 channels grew the most favorably, reaching EY=344±113kPa and GAG and collagen contents of 10.8±1.2% and 2.2±0.2% of construct wet weight, respectively. Constructs with 27 channels had significantly less deposited GAG than other groups. Channeled constructs given 1 or 10ng/mL TGF-β developed similar properties. Without TGF-β, constructs with 0 or 12 channels exhibited properties that were indistinguishable, and lower than TGF-β-supplemented constructs. Taken together, these results emphasize that nutrient channels are effective only in the presence of TGF-β, and indicate that spacings equivalent to 12 channels in ∅10mm constructs can be employed in articular-layer-sized constructs with reduced dosages of TGF-β.
软骨组织工程是治疗骨关节炎的一种很有前景的方法。然而，目前的技术所产生的组织太小，无法应用于临床。越来越紧密排列的通道有助于克服厘米大小的软骨细胞 - 琼脂糖构建体中的营养物质运输限制，但尚未确定在如此大的构建体中重现天然软骨组成和力学性能的最佳通道间距。短暂的活性转化生长因子 -β（TGF-β）处理能够持续重现构建体中的天然压缩杨氏模量（EY）和糖胺聚糖（GAG）含量，但10ng/mL的标准剂量会加剧基质异质性。为了最终生产出关节层大小的构建体，我们必须首先优化通道间距，并研究TGF-β在通道效用中的作用。我们将直径10mm的构建体培养6 - 8周，这些构建体分别有0、12、19或27个营养通道（直径1mm），并添加0、1或10ng/mL的TGF-β；随后对它们进行力学、生化和组织学分析。有12或19个通道的构建体生长最为良好，EY达到344±113kPa，GAG和胶原蛋白含量分别为构建体湿重的10.8±1.2%和2.2±0.2%。有27个通道的构建体沉积的GAG明显少于其他组。给予1或10ng/mL TGF-β的带通道构建体表现出相似的性能。在没有TGF-β的情况下，有0或12个通道的构建体表现出无法区分的性能，且低于添加TGF-β的构建体。综上所述，这些结果强调营养通道仅在存在TGF-β时才有效，并表明在直径10mm的构建体中相当于12个通道的间距可用于关节层大小的构建体，并减少TGF-β的剂量。
