Department of Bioengineering, University of California, Riverside, CA, USA.
Department of Bioengineering, University of California, Riverside, CA, USA.
Acta Biomater. 2018 Jan 15;66:166-176. doi: 10.1016/j.actbio.2017.11.020. Epub 2017 Nov 8.
Hydrogels have shown great potential for cartilage tissue engineering applications due to their capability to encapsulate cells within biomimetic, 3-dimensional (3D) microenvironments. However, the multi-step fabrication process that is necessary to produce cell/scaffold constructs with defined dimensions, limits their off-the-shelf translational usage. In this study, we have developed a hybrid scaffolding system which combines a thermosensitive hydrogel, poly(ethylene glycol)-poly(N-isopropylacrylamide) (PEG-PNIPAAm), with a biodegradable polymer, poly(ε-caprolactone) (PCL), into a composite, electrospun microfibrous structure. A judicious optimization of material composition and electrospinning process produced a structurally self-supporting hybrid scaffold. The reverse thermosensitivity of PEG-PNIPAAm allowed its dissolution/hydration upon cell seeding within a network of PCL microfibers while maintaining the overall scaffold shape at room temperature. A subsequent temperature elevation to 37 °C induced the hydrogel's phase transition to a gel state, effectively encapsulating cells in a 3D hydrogel without the use of a mold. We demonstrated that the hybrid scaffold enhanced chondrogenic differentiation of human mesenchymal stem cells (hMSCs) based on chondrocytic gene and protein expression, which resulted in superior viscoelastic properties of the cell/scaffold constructs. The hybrid scaffold enables a facile, single-step cell seeding process to inoculate cells within a 3D hydrogel with the potential for cartilage tissue engineering.
Hydrogels have demonstrated the excellent ability to enhance chondrogenesis of stem cells due to their hydrated fibrous nanostructure providing a cellular environment similar to native cartilage. However, the necessity for multi-step processes, including mixing of hydrogel precursor with cells and subsequent gelation in a mold to form a defined shape, limits their off-the-shelf usage. In this study, we developed a hybrid scaffold by combining a thermosensitive hydrogel with a mechanically stable polymer, which provides a facile means to inoculate cells in a 3D hydrogel with a mold-less, single step cell seeding process. We further showed that the hybrid scaffold enhanced chondrogenesis of mesenchymal stem cells, demonstrating its potential for cartilage tissue engineering.
由于水凝胶能够在仿生 3D 微环境中包封细胞，因此在软骨组织工程应用中显示出巨大的潜力。然而，为了生产具有确定尺寸的细胞/支架结构，需要多步制造工艺，这限制了其现货翻译的使用。在这项研究中，我们开发了一种混合支架系统，该系统将温敏水凝胶聚（乙二醇）-聚（N-异丙基丙烯酰胺）（PEG-PNIPAAm）与可生物降解的聚合物聚（ε-己内酯）（PCL）结合到一个复合的电纺微纤维结构中。通过对材料组成和静电纺丝工艺的合理优化，产生了一种结构上自支撑的混合支架。PEG-PNIPAAm 的反向温敏性允许其在 PCL 微纤维网络内包封细胞的同时在室温下溶解/水合，同时保持整个支架的形状。随后将温度升高至 37°C 会引起水凝胶向凝胶状态的相转变，无需使用模具即可有效地将细胞包封在 3D 水凝胶中。我们证明，混合支架通过基于软骨细胞基因和蛋白表达的软骨分化增强了人骨髓间充质干细胞（hMSC）的分化，从而导致细胞/支架结构的粘弹性更好。该混合支架可实现简便的单步细胞接种过程，将细胞接种到 3D 水凝胶中，具有用于软骨组织工程的潜力。
由于水凝胶的水合纤维纳米结构提供了类似于天然软骨的细胞环境，因此它已经证明了增强干细胞软骨形成的出色能力。然而，包括将水凝胶前体与细胞混合以及随后在模具中凝胶化以形成确定形状的多步过程的必要性，限制了其现货使用。在这项研究中，我们通过将热敏水凝胶与机械稳定的聚合物结合来开发混合支架，这为使用无模具的单步细胞接种过程将细胞接种到 3D 水凝胶中提供了简便的方法。我们进一步表明，混合支架增强了间充质干细胞的软骨形成，证明了其在软骨组织工程中的潜力。
