Li Jun, Cui Xiaolin, Lindberg Gabriella C J, Alcala-Orozco Cesar R, Hooper Gary J, Lim Khoon S, Woodfield Tim B F
Christchurch Regenerative Medicine and Tissue Engineering (CReaTE) Group, Department of Orthopedic Surgery & Musculoskeletal Medicine, Centre for Bioengineering & Nanomedicine, University of Otago Christchurch, Christchurch, New Zealand.
Light Activated Biomaterials (LAB) Group, Department of Orthopedic Surgery & Musculoskeletal Medicine, Centre for Bioengineering & Nanomedicine, University of Otago Christchurch, Christchurch, New Zealand.
Biofabrication. 2022 Apr 13;14(3). doi: 10.1088/1758-5090/ac6051.
Bone regeneration of critical-sized bone defects, bone fractures or joint replacements remains a significant clinical challenge. Although there has been rapid advancement in both the fields of bone tissue engineering and additive manufacturing, functional bone implants with rapid vascularization capacity to ensure osseointegration and long-term biological fixation in large bone defects remains limited in clinics. In this study, we developed anvascularized bone implant by combining cell-laden hydrogels with direct metal printed (DMP) porous titanium alloys (Ti-6Al-4V). A 5 wt% allylated gelatin (GelAGE), was utilized to co-encapsulate human mesenchymal stromal cells (hMSCs) and human umbilical vein endothelial cells (HUVECs) to investigate concurrent osteogenic and vasculogenic performance. DMP macro-porous Ti-6Al-4V scaffolds were subsequently infused/enriched with cell-laden GelAGE to examine the feasibility to deliver cells and engineer vascular-like networks in the hybrid implant. Furthermore, as a proof of concept, a full-scale porous Ti-6Al-4V acetabular cup was impregnated with cell-laden hydrogel to validate the clinical potential of this strategy. The vasculogenic potential was evaluated by examining micro-capillary formation coupled with capillary network maturation and stabilization. Osteogenic differentiation was assessed via alkaline phosphatase activity as well as osteocalcin and osteopontin expression. Our results suggested that GelAGE supported HUVECs spreading and vascular-like network formation, along with osteogenesis of hMSCs. Titanium hybrid constructs with cell-laden hydrogel demonstrated enhanced osteogenesis with similar vasculogenic capability compared to the cell-laden hydrogel alone constructs. The full-scale implant with cell-laden hydrogel coating similarly showed cell distribution and spreading, implying the potential for further clinical application. Our study presents the feasibility of integrating bio-functional hydrogels with porous titanium implants to fabricate a vascularized hybrid construct with both mechanical support and preferable biological functionality (osteogenesis/vasculogenesis), which paves the way for improved strategies to enhance bone regeneration in complex large bone defects achieving long-term bone-implant fixation.
临界尺寸骨缺损、骨折或关节置换的骨再生仍然是一项重大的临床挑战。尽管骨组织工程和增材制造领域都取得了快速进展，但在临床上，具有快速血管化能力以确保在大骨缺损中实现骨整合和长期生物固定的功能性骨植入物仍然有限。在本研究中，我们通过将载细胞水凝胶与直接金属打印（DMP）多孔钛合金（Ti-6Al-4V）相结合，开发了一种血管化骨植入物。使用5 wt%烯丙基化明胶（GelAGE）共包封人间充质基质细胞（hMSCs）和人脐静脉内皮细胞（HUVECs），以研究同时发生的成骨和血管生成性能。随后，将载细胞的GelAGE注入/富集到DMP大孔Ti-6Al-4V支架中，以检验在混合植入物中递送细胞并构建类血管网络的可行性。此外，作为概念验证，将全尺寸多孔Ti-6Al-4V髋臼杯用载细胞水凝胶浸渍，以验证该策略的临床潜力。通过检查微毛细血管形成以及毛细血管网络的成熟和稳定来评估血管生成潜力。通过碱性磷酸酶活性以及骨钙素和骨桥蛋白表达来评估成骨分化。我们的结果表明，GelAGE支持HUVECs的铺展和类血管网络形成，以及hMSCs的成骨作用。与仅载细胞水凝胶构建体相比，带有载细胞水凝胶的钛混合构建体表现出增强的成骨作用和相似的血管生成能力。带有载细胞水凝胶涂层的全尺寸植入物同样显示出细胞分布和铺展，这意味着具有进一步临床应用的潜力。我们的研究提出了将生物功能水凝胶与多孔钛植入物整合以制造具有机械支撑和良好生物功能（成骨/血管生成）的血管化混合构建体的可行性，这为改进策略以增强复杂大骨缺损中的骨再生并实现长期骨植入固定铺平了道路。
