Optimisation of 3D Printed Hydrogel Scaffolds for Use in Tissue Engineering

严重受损的组织或器官可能需要器官或组织移植来替代或重建受损的组织或器官。目前器官移植存在的问题包括供体器官短缺和免疫排斥(1)。这一领域的研究是极其重要的，因为组织工程可能取代对器官和组织移植的需求，也可能克服器官移植所涉及的缺点。此外，在2010年进行的一项研究得出的结论是，全世界只有10%的器官移植需求得到满足，这突出了组织工程进步的必要性(2)。水凝胶是一种由亲水性聚合物组成的网状结构，其柔韧性可以随着水的含量而变化。水凝胶可以吸收其干重的10%到数千倍的水分。它们可以保留大量的水或生物液体，并且具有像活组织一样柔软的稠度，这种特性使它们成为体内各种应用的理想物质(4)。聚合物基体中的亲水性基团使水的吸收成为可能。水凝胶由于其生物相容性和对水含量的控制而与组织工程相关。这可以决定它的一致性，以满足材料和生物学的要求，以治疗或替代组织，并可能在未来，更复杂的结构，如器官(4)(5)。组织支架某些疾病可导致严重的功能缺陷。需要支持性材料来恢复病变器官与周围组织之间的健康相互作用(6)。支持支架用于引导组织生长以帮助再生过程(3)。支架提供结构支撑和构造形状，是细胞附着和生长的场所，通常具有可生物降解和生物相容性(7)。在体内使用的植入支架应该与它所支撑的周围细胞外基质的机械刚度相匹配。组织工程师面临的一个挑战是如何应用完全可生物降解的生物材料。这是因为生物可降解材料在机械强度、期望的生物可降解持续时间和可控制的成本之间取得完美平衡的可能性仍然有限(8)。PVAPVA因其生物相容性、可生物降解性、无毒性、水溶性、耐化学性和相对便宜的价格，在许多涉及其使用的文章中受到了广泛的欢迎(9)（10）。然而，聚乙烯醇还没有被用作体内的支架。尽管它是无毒的，但与之相关的风险尚未得到充分的记录，降解后的分解产物可能是有毒的，因此不是完全安全的（11）。使用纯聚乙烯醇有局限性，如刚度，但这些可以通过形成复合材料来克服。许多研究将聚乙烯醇复合材料用于许多不同的目的。本项目有两个主要目标：1)评估设计（配方）对PVA和pvac复合水凝胶支架加工的影响，以提供足够的机械支持和支持细胞生长。2)评估制造（传统与3D打印）对运输特性的影响，因此必须模拟ECM和支持细胞生长的能力。参考文献1。https://doi.org/10.1098/rsif.2006.01242。https://doi.org/10.1016/j.msec.2021.1119273。https://doi.org/10.1016/s0168 - 583 x 00118 - 44(99)。https://doi.org/10.1016/j.msec.2015.07.0535。https://doi.org/10.1007/s10965 - 013 - 0273 - 76。https://doi.org/10.1016/j.jconrel.2020.11.0447。https://doi.org/10.1007/978 - 1 - 349 - 09574 - 2 - _248。https://doi.org/10.3389/fbioe.2019.001279。https://doi.org/10.1179/1753555713Y.000000011510。https://doi.org/10.1021/bm200083n11。https://doi.org/10.1016/j.ijbiomac.2018.07.159

Tissues or organs that have been severely damaged may need organ or tissue transplantation to replace or reconstruct the devastated tissues or organs. Problems in current organ transplantation include shortage of donated organs and immune rejection(1). This area of research is extremely important as tissue engineering could possibly replace the need for organ and tissue transplants and may also overcome the drawbacks involved in organ transplantation. There is a shortage of organ donors moreover in 2010, a study was conducted that concluded that only 10% of the worldwide organ transplant needs weremet, which highlights the need for the advancement of tissue engineering(2).HydrogelsHydrogels are a network of hydrophilic polymers where the degree of flexibility can change due to water content. Hydrogels can absorb water in the amount from 10% up to thousands of times their dry weight(3). They can retain a large amount of water or biological fluids and are characterized by a soft consistency like living tissues and this quality make them an ideal substance for a variety of applications within the body(4). The absorption of water is made possible by hydrophilic groups within the polymer matrix. Hydrogels are relevant to tissue engineering due to their biocompatibility and control of water content. This can determine its consistency to meet both material and biological requirements to treat or replace tissues and possibly in the future, more complex structures such as organs(4)(5).Tissue ScaffoldsCertain diseases can lead to significant functional defects. Supportive materials are needed to restore healthy interactions between diseased organs and surrounding tissues(6). Supportive scaffolds are used for guided tissue growth to aid regenerative processes(3). Scaffolds provide structural support and shape to construct, a place for cell attachment and growth and are usually biodegradable and biocompatible(7).The implanted scaffold used in the body should aim to match the mechanical stiffness of the surrounding extracellular matrix that it is supporting. A challenge faced by tissue engineers is the application of a fully biodegradable biomaterial. This is because biodegradable materials that have the perfect balance of mechanical strength, desired duration of biodegradability, with manageable costs is still limited(8).PVAPVA has received great popularity with many articles involving its use due to its biocompatibility, biodegradability, non-toxicity, solubility in water, chemical resistance and relatively inexpensive price(9)(10). However, PVA has still not been used as a scaffold within the body. The risks associated with it have not been fully documented despite it being nontoxic, the break down products after degradation may be toxic and thus not entirely safe(11). There are limitations with the use of pure PVA such as stiffness, however these may be overcome by forming a composite. Many studies have used PVA composites for many different purposes.Research and Objective PlanThere are two main objectives for this project which are to:1) assess the impact of design (formulation) on the processing of PVA and PVAcomposites hydrogel scaffolds to provide adequate mechanical support and supportcell growth.2) evaluate the effect of manufacturing (conventional versus 3D printing) on transportsproperties and thus the ability this must mimic the ECM and support cell growth.References1. https://doi.org/10.1098/rsif.2006.01242. https://doi.org/10.1016/j.msec.2021.1119273. https://doi.org/10.1016/S0168-583X(99)00118-44. https://doi.org/10.1016/j.msec.2015.07.0535. https://doi.org/10.1007/s10965-013-0273-76. https://doi.org/10.1016/j.jconrel.2020.11.0447. https://doi.org/10.1007/978-1-349-09574-2_248. https://doi.org/10.3389/fbioe.2019.001279. https://doi.org/10.1179/1753555713Y.000000011510. https://doi.org/10.1021/bm200083n11. https://doi.org/10.1016/j.ijbiomac.2018.07.159