Bioactive signal gradients to engineer TMJ condyle osteochondral constructs

描述（由申请人提供）：本申请的长期目标是设计无缝骨软骨结构，用于关节退行性变患者的临床治疗，特别是颞下颌关节（TMJ）。使用现成的、无争议的、低免疫原性的人类细胞来源和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，而且由于对这个关节的研究相对较少，它不属于矫形外科的范畴。本提案的总体目标是利用人脐带基质（HUCM）干细胞和微粒技术来设计无缝骨软骨结构。主要假设是，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干细胞将导致具有比单独培养的任何区域更优越的软骨和骨区域的骨软骨结构，导致具有异质软骨组织的连续过渡区域，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)选择均匀支架的微粒直径，以及3)设计连续骨软骨结构。这种新型支架由直径离散的PLGA微粒构成，将被开发用于从均质支架中提供所需的转化生长因子- β 1 （tgf - β 1）和骨形态发生蛋白-2 （BMP-2）的释放。生长因子的活性将得到保证，并在一段时间内保持梯度的能力将得到验证。这个开发/表征阶段将为组织工程阶段的生长因子提供一个包封浓度，组织工程阶段将开始一项研究，以确定基于独立的均质成骨和软骨支架的适当微粒大小。在这个阶段，我们将创建具有两种不同梯度分布的支架，这些生长因子在PLGA支架内具有相反的浓度分布（线性或s型）。生长因子的信号梯度是人类发育的基本组成部分，合成模拟这种梯度可能有利于组织工程。此外，这种对骨和软骨谱系的最初承诺有助于骨和软骨细胞之间的相互诱导信号。该研究提出了一种创新的方法来肌肉骨骼组织工程，利用新的有吸引力的细胞来源，并通过新的支架设计产生生物活性信号梯度。

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.