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取代或重建受损的组织或器官。目前器官移植中存在的问题包括供体器官短缺和免疫排斥。这一研究领域极其重要，因为组织工程可能取代器官和组织移植的需要，也可能克服器官移植所涉及的缺点。此外，2010年进行的一项研究得出的结论是，全球器官移植需求的10%得到了满足，这突显了推进组织工程的必要性(2)。水凝胶是一种亲水性聚合物网络，其柔韧性可以随着水分的变化而改变。水凝胶可以吸收10%至几千倍于其干重的水。它们可以保留大量的水或生物液体，其特点是像活组织一样柔软稠密，这一特性使其成为人体内各种应用的理想物质(4)。聚合物基质中的亲水基团使水的吸收成为可能。水凝胶因其生物相容性和水含量的可控性而与组织工程相关。这可以确定其一致性，以满足治疗或替换组织的材料和生物要求，并可能在未来满足更复杂的结构，如器官(4)(5)。问题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疾病器官和周围组织之间的健康互动(6)。支撑性支架用于引导组织生长，以帮助再生过程(3)。支架为构建细胞附着和生长提供了结构支撑和形状，通常是可生物降解和生物兼容的(7)。体内使用的植入支架的目标应该是匹配它所支撑的周围细胞外基质的机械硬度。组织工程师面临的一个挑战是应用一种完全可生物降解的生物材料。这是因为具有机械强度、期望的生物降解性持续时间和可管理成本的可生物降解材料仍然有限(8)。PVAPVA因其生物兼容性、生物降解性、无毒、在水中的溶解性、耐化学性和相对便宜的价格而受到许多涉及其使用的文章的欢迎(9)(10)。然而，PVA仍然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，降解后的产品可能是有毒的，因此并不完全安全(11)。使用纯PVA有一定的局限性，例如刚性，但是可以通过形成复合材料来克服这些限制。研究和目的本项目的两个主要目标是：1)评估设计(配方)对PVA和PVA复合材料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(传统打印与3D打印)对运输性能的影响，从而评估其必须模仿细胞外基质和支持细胞生长的能力。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

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