Laboratory of Bioregenerative Medicine & Surgery, Division of Plastic Surgery, Weill Cornell Medical Center, 1300 York, Room A-821, New York, NY 10021, United States.
Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, 121A Weill Hall, Ithaca, NY 14853, United States.
Acta Biomater. 2019 Jun;91:144-158. doi: 10.1016/j.actbio.2019.04.027. Epub 2019 Apr 18.
Insufficient vascularization of currently available clinical biomaterials has limited their application to optimal wound beds. We designed a hydrogel scaffold with a unique internal microstructure of differential collagen densities to induce cellular invasion and neovascularization.
Microsphere scaffolds (MSS) were fabricated by encasing 1% (w/v) type 1 collagen microspheres 50-150 μm in diameter in 0.3% collagen bulk. 1% and 0.3% monophase collagen scaffolds and Integra® disks served as controls. Mechanical characterization as well as in vitro and in vivo invasion assays were performed. Cell number and depth of invasion were analyzed using Imaris™. Cell identity was assessed immunohistochemically.
In vitro, MSS exhibited significantly greater average depth of cellular invasion than Integra® and monophase collagen controls. MSS also demonstrated significantly higher cell counts than controls. In vivo, MSS revealed significantly more cellular invasion spanning the entire scaffold depth at 14 days than Integra®. CD31+ expressing luminal structures suggestive of neovasculature were seen within MSS at 7 days and were more prevalent after 14 days. Multiphoton microscopy of MSS demonstrated erythrocytes within luminal structures after 14 days.
By harnessing simple architectural cues to induce cellular migration, MSS holds great potential for clinical translation as the next generation dermal replacement product.
Large skin wounds require tissue engineered dermal substitutes in order to promote healing. Currently available dermal replacement products do not always adequately incorporate into the body, especially in complex wounds, due to poor neovascularization. In this paper, we present a hydrogel with an innovative microarchitecture that is composed of dense type I collagen microspheres suspended in a less-dense collagen bulk. We show that cell invasion into the scaffold is driven solely by mechanical cues inherent within this differential density interface, and that this induces robust vascular cell invasion both in vitro and in a rodent model. Our hydrogel performs favorably compared to the current clinical gold standard, Integra®. We believe this hydrogel scaffold may be the first of the next generation of dermal replacement products.
目前可用的临床生物材料血管化不足，限制了其在最佳创面床中的应用。我们设计了一种水凝胶支架，具有独特的内部微观结构，胶原密度不同，可诱导细胞浸润和新血管生成。
通过将直径为 50-150μm 的 1%（w/v）I 型胶原微球包裹在 0.3%胶原基质中，制备微球支架（MSS）。1%和 0.3%单相胶原支架和 Integra®盘作为对照。进行了力学特性以及体外和体内浸润试验。使用 Imaris™分析细胞数量和浸润深度。免疫组织化学评估细胞特性。
体外，MSS 的细胞平均浸润深度明显大于 Integra®和单相胶原对照。MSS 的细胞计数也明显高于对照。体内，14 天时，MSS 显示出比 Integra®更广泛的细胞浸润，贯穿整个支架深度。7 天时，MSS 中可见到表达 CD31 的管腔结构，提示有新血管生成。14 天后，这些结构更为常见。MSS 的多光子显微镜显示，14 天后，管腔结构内有红细胞。
通过利用简单的结构线索来诱导细胞迁移，MSS 作为下一代真皮替代产品具有很大的临床转化潜力。
大的皮肤伤口需要组织工程化的真皮替代物来促进愈合。目前可用的真皮替代物由于新血管生成不良，并不总是能充分融入体内，尤其是在复杂伤口中。在本文中，我们提出了一种具有创新微结构的水凝胶，由悬浮在较稀胶原基质中的致密 I 型胶原微球组成。我们表明，细胞对支架的浸润完全是由这种密度差异界面固有的机械线索驱动的，这在体外和啮齿动物模型中都能诱导强大的血管细胞浸润。与目前的临床金标准 Integra®相比，我们的水凝胶表现良好。我们相信这种水凝胶支架可能是下一代真皮替代产品的首例。
