Bioengineered soft tissues on any meaningful scale or complexity must incorporate aspects of the functional tissue, namely a vasculature, providing cells oxygen and nutrients critical for their survival. However, the ability of tissue engineering strategies to promote a fast revascularization is critically limited. Particularly in endodontic regenerative therapies, the complicated anatomy of the root canal system, and the narrow apical access limit the supply of new blood vessels and pulp tissue ingrowth.

Here we characterize the viscoelastic and microstructural properties of a class of injectable hyaluronic acid (HA) hydrogels formed in situ, reinforced with cellulose nanocrystals (CNCs) and enriched with platelet lysate (PL), and test its ability to promote cells recruitment and proangiogenic activity in vitro. The incorporation of CNCs enhanced the stability of the materials against hydrolytic and enzymatic degradation. Moreover, the release of the chemotactic and pro-angiogenic growth factors (GFs) (PDGF and VEGF) from the PL-laden hydrogels showed an improved sustained profile proportional to the amount of incorporated CNCs. The PL-laden hydrogels exhibited preferential supportive properties of encapsulated human dental pulp cells (hDPCs) in in vitro culture conditions.

Finally, PL-laden hydrogels stimulated chemotactic and pro-angiogenic activity by promoting hDPCs recruitment and cell sprouting in hDPCs/human umbilical vein endothelial cell co-cultures in vitro, and in an ex vivo model. These results support the use of the combined system as a scaffold for GFs delivery and cells recruitment, thereby exhibiting great clinical potential in treating injuries in vascularized tissues.

Statement of Significance

Innovative strategies for improved chemotactic and pro-angiogenic features of TE constructs are needed. In this study, we developed an injectable HA/CNC/PL hydrogel with improved structural and biologic properties, that not only provide a sustained release of chemotactic and proangiogenic GFs from PL but also enhance the cells’ viability and angiogenic activity. As a result of their unique traits, the developed hydrogels are ideally suited to simultaneously act as a GFs controlled delivery system and as a supportive matrix for cell culture, recruitment, and revascularization induction, holding great potential for the regeneration of vascularized soft tissues, such as the dentin-pulp complex.

任何有意义的规模或复杂性的生物工程软组织都必须结合功能组织的各个方面，即脉管系统，为细胞提供对其生存至关重要的氧气和营养。但是，组织工程策略促进快速血运重建的能力受到严重限制。特别是在牙髓再生治疗中，根管系统的解剖结构复杂，并且根尖通道狭窄，限制了新血管的供应和牙髓组织的向内生长。

在这里，我们表征一类可注射的透明质酸（HA）水凝胶的粘弹性和微结构特性，这些水凝胶原位形成，用纤维素纳米晶体（CNC）增强并富含血小板裂解物（PL），并测试其促进细胞募集和促血管生成活性的能力。体外。CNC的加入增强了材料抵抗水解和酶促降解的稳定性。此外，载有PL的水凝胶释放趋化性和促血管生成生长因子（GFs）（PDGF和VEGF）显示出与结合的CNC数量成比例的改善的持续性。载有PL的水凝胶在体外显示出封装的人类牙髓细胞（hDPC）的优先支持特性 文化条件。

最后，载有PL的水凝胶可通过在体外和离体模型中促进hDPC /人脐静脉内皮细胞共培养物中的hDPC募集和细胞发芽来刺激趋化活性和促血管生成活性。这些结果支持将组合系统用作GFs递送和细胞募集的支架，从而在治疗血管化组织中的损伤方面显示出巨大的临床潜力。

重要声明

需要用于改善TE构建体的趋化性和促血管生成特征的创新策略。在这项研究中，我们开发了具有改善的结构和生物学特性的可注射HA / CNC / PL水凝胶，它不仅可以从PL中持续释放趋化性和促血管生成的GF，而且还可以增强细胞的活力和血管生成活性。由于其独特的特性，开发的水凝胶非常适合同时用作GFs控制的递送系统和细胞培养，募集和血运重建诱导的支持基质，具有再生血管化软组织的巨大潜力，例如作为牙本质浆复合物。