Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, USA.
Center for Engineering Complex Tissues, University of Maryland, College Park, Maryland, USA.
J Biomed Mater Res A. 2021 Oct;109(10):1893-1904. doi: 10.1002/jbm.a.37181. Epub 2021 Apr 2.
The increasing prevalence of chronic, nonhealing wounds necessitates the investigation of full-thickness skin substitutes conducive to host integration and wound closure. Extracellular matrix (ECM)-based hydrogel scaffolds mimic the physiological matrix environment of dermal cells, thereby conferring favorable cellular adhesion, infiltration, and proliferation. However, low-concentration ECM hydrogels rapidly lose mechanical strength as they degrade, leaving them susceptible to shrinkage from fibroblast-mediated contraction. Conversely, high-concentration ECM hydrogels are typically too dense to permit nutrient diffusion and cellular migration. This study investigates the design and fabrication of a graded-concentration hydrogel composed of porcine urinary bladder matrix (UBM) as a dermal scaffold for potential use in chronic wound treatment. Our method of UBM isolation and decellularization effectively removed native DNA while preserving matrix proteins. Hydrogels composed of a range of decellularized UBM (dUBM) concentrations were characterized and used to design a three-tiered gradient hydrogel that promoted cellular activity and maintained structural integrity. The gradient dUBM hydrogel showed stability of cross-sectional area during collagenase degradation, despite considerable loss of mass. The gradient dUBM hydrogel also resisted fibroblast-mediated contraction while supporting high surface cell viability, demonstrating the mechanical support provided by denser layers of dUBM. Overall, incorporation of an ECM concentration gradient into a porcine UBM-based hydrogel scaffold capitalizes on the unique advantages of both high and low-concentration ECM hydrogels, and mitigates the structural weaknesses that have limited the efficacy of hydrogel dermal scaffolds for chronic wounds. Our gradient design shows promise for future development of stable, pro-regenerative wound scaffolds with customized architectures using 3D printing.
慢性、非愈合性伤口的患病率不断增加，这就需要研究能够促进宿主整合和伤口闭合的全厚皮肤替代品。基于细胞外基质 (ECM) 的水凝胶支架模拟了真皮细胞的生理基质环境，从而赋予了良好的细胞黏附、渗透和增殖能力。然而，低浓度的 ECM 水凝胶在降解时会迅速失去机械强度，容易受到成纤维细胞介导的收缩而收缩。相反，高浓度的 ECM 水凝胶通常太密集，无法允许营养物质扩散和细胞迁移。本研究探讨了设计和制造一种由猪尿囊膜基质 (UBM) 组成的分级浓度水凝胶，作为潜在的慢性伤口治疗用真皮支架。我们的 UBM 分离和脱细胞方法有效地去除了天然 DNA，同时保留了基质蛋白。对不同浓度脱细胞 UBM (dUBM) 组成的水凝胶进行了表征，并用于设计三层梯度水凝胶，以促进细胞活性和维持结构完整性。尽管质量损失相当大，但梯度 dUBM 水凝胶在胶原酶降解过程中仍保持了横截面面积的稳定性。梯度 dUBM 水凝胶还能抵抗成纤维细胞介导的收缩，同时支持高表面细胞活力，表明更密集的 dUBM 层提供了机械支撑。总之，将 ECM 浓度梯度纳入基于猪 UBM 的水凝胶支架中，利用了高浓度和低浓度 ECM 水凝胶的独特优势，并减轻了限制水凝胶真皮支架治疗慢性伤口效果的结构弱点。我们的梯度设计有望为使用 3D 打印技术开发具有定制结构的稳定、促进再生的伤口支架提供未来的发展方向。
