Bioactive signal gradients to engineer TMJ condyle osteochondral constructs

描述(申请人提供)：这项申请的长期目标是设计无缝的骨软骨结构，用于临床治疗退行性关节，特别是颞下颌关节(TMJ)。使用容易获得、免疫原性低、无争议的人类细胞来源和FDA批准的生物材料，将促进本提案中描述的核心技术开发后的转化研究阶段。TMJ是我们关注的焦点，因为相关疾病的发病率相当高，而且由于对骨科伞外的这个关节的研究相对较少。这项提议的总体目标是使用人脐带基质干细胞和微粒子技术来设计无缝的骨软骨结构。主要的假设是，在一种新的梯度驱动支架设计方法中，使用软骨诱导和骨诱导的HUCM干细胞将导致具有优于单独培养的软骨和骨区域的骨软骨结构，从而导致具有异质软骨组织的连续过渡区，其更类似于天然软骨的带状组织。为了验证这一假设，我们提出了以下具体目标：1)开发和表征新型梯度支架，2)选择具有均匀支架的微粒直径，3)构建连续的骨软骨结构。这种由直径离散的PLGA微粒构建的新型支架将被开发成从均一支架中提供所需的转化生长因子-β1(转化生长因子-β1)和骨形态发生蛋白-2(BMP-2)的释放轮廓。将确保生长因子的活性，然后将验证随时间保持梯度的能力。这一开发/表征阶段将为组织工程阶段的生长因子提供一个包埋浓度，该阶段将从一项研究开始，以确定基于单独的均质成骨和成软骨支架的合适的微粒子尺寸。在那个阶段，我们将创建支架，展示这些生长因子的两种不同的梯度分布，在PLGA支架内具有相反的浓度分布(线性或S形)。生长因子的信号梯度是人类发育的一个基本部分，综合模拟这种梯度很可能对组织工程有利。此外，这种对骨性和软骨性血统的初步承诺有助于骨和软骨细胞之间的相互感应信号。这项研究提出了一种创新的肌肉骨骼组织工程方法，利用一种新的有吸引力的细胞源，并通过新颖的支架设计创建生物活性信号梯度。

DESCRIPTION (provided by applicant): The long-term objective of this application is to engineer seamless osteochondral constructs for clinical treatment of patients with degenerated joints, in particular the temporomandibular joint (TMJ). The use of a readily available, non-controversial human cell source with low immunogenicity and an FDA-approved biomaterial will facilitate the translational research phase after the core technology described in this proposal is developed. The TMJ is the focus of our attention due to the considerable morbidity of related disorders and due to the relative paucity of research attention paid to this joint that falls outside of the orthopaedic umbrella. The overall objective of this proposal is to use human umbilical cord matrix (HUCM) stem cells and microparticle technology to engineer seamless osteochondral constructs. The chief hypothesis is that using chondro-induced and osteo-induced HUCM stem cells in a novel gradient-driven scaffold design approach will lead to an osteochondral construct with superior cartilage and bony regions than either region cultured alone, resulting in a continuous transition region with a heterogeneous cartilage organization that better resembles zonal organization in native cartilage. To test this hypothesis, we propose the following specific aims: 1) to develop and characterize the novel gradient scaffold, 2) to select microparticle diameters with homogeneous scaffolds, and 3) to engineer a continuous osteochondral construct. The novel scaffolds, constructed from PLGA microparticles of discrete diameters, will be developed to provide the desired release profile of transforming growth factor-beta1 (TGF-beta1) and bone morphogenic protein-2 (BMP-2) from homogeneous scaffolds. Growth factor activity will be ensured and ability to maintain a gradient over time will then be verified. This development/characterization phase will provide an encapsulation concentration for the growth factors in the tissue engineering phase, which will begin with a study to determine an appropriate microparticle size based on separate homogeneous osteogenic and chondrogenic scaffolds. At that stage, we will create scaffolds exhibiting two distinct gradient profiles of these growth factors with opposing concentration profiles (linear or sigmoidal) within the PLGA scaffold. Signal gradients of growth factors are a fundamental part of human development and it is probable that synthetically mimicking such gradients will be beneficial to tissue engineering. Moreover, this initial commitment to osseous and cartilaginous lineages lends to mutually inductive signals between bone and cartilage cells. The proposed research presents an innovative approach to musculoskeletal tissue engineering by utilizing a new attractive cell source and creating bioactive signal gradients via novel scaffold design.