Experimental Model For Pressure Ulcers In Human Skin: The Role of Aging and ECM

描述(申请人提供)：我们的目标是开发一个体外实验模型来研究导致老年人皮肤愈合障碍和压疮的皮肤组织变化。这项研究将确定人类皮肤细胞外基质(ECM组成、组织和周转)的年龄相关变化，以及这些变化如何导致其机械、细胞和分子性质的改变。此外，我们还将确定压应力(压力)如何影响这些机械、细胞和分子特性。压力性溃疡的定义是由于皮肤持续受压而导致的皮肤被膜破裂。据估计，每年有250万压疮需要在医院接受治疗，主要针对老年人口，每年的总费用估计为22亿至36亿美元。这不包括疼痛、痛苦和其他与压疮相关的疾病。目前，还没有FDA批准的治疗方法在随机临床试验中确定对压疮的疗效，也没有实验模型。因此，我们的目标是开发一种实验模型来研究导致压疮发展和损害愈合的变化。在这份提案中，我们将使用我们的机械植体测试系统(METS)对人体皮肤植体进行压缩加载(应力)，并确定产生ECM病理性变化的时间和负载大小、机械性能、导致伤口愈合受损和压疮发展的细胞过程。此外，我们将使用年轻人(25-35岁)、中年(40-55岁)和老年人(60-75岁)的皮肤来确定与年龄相关的变化，这些变化将导致压疮的发生。在没有或存在压缩负荷的情况下，将在皮肤标本中测量以下参数：1)细胞外基质(ECM)特性(肌腱、纤维连接蛋白、弹性蛋白、前胶原、胶原、基质金属蛋白酶(MMP))及其信号(整合素、FAK和MAPK)；2)皮肤的机械特性(拉伸强度)；3)应用生物力学检测和标准分子生物学技术(免疫组织化学、Western blots、实时定量聚合酶链式反应)检测细胞形态/生物学(增殖、凋亡和生长因子/细胞因子产生)。我们的长期目标是消除IV期压疮，并降低老年人口中压疮的发病率、死亡率和痛苦。本申请中提出的实验方法将为我们提供机会来确定导致老年人压疮的变化，这是开发新的治疗方式的最终第一步。开发一个实验模型来研究导致老年人皮肤压疮(压疮)的机制是确定压疮病因(发病机制)的第一步。目前，还没有足够的实验模型和FDA批准的治疗方法来治疗这些溃疡，因此我们提出的研究将对未来开发治疗这种毁灭性疾病的潜在疗法产生很大影响。压疮的实验模型不仅将提供对发病机制的潜在理解，而且还将允许对潜在的治疗方式进行临床前测试。

DESCRIPTION (provided by applicant): Our goal is to develop an in vitro experimental model to study skin tissue changes that lead to impaired healing and pressure ulcers in elderly. This study will determine the age-related changes in the extracellular matrix (ECM composition, organization and turnover) in human skin and how these changes contribute to its altered mechanical, cellular and molecular properties. Furthermore, we will determine how compressive stress (pressure) affects these mechanical, cellular and molecular properties. A pressure ulcer is defined as a break in the integument usually caused by continuous pressure to the skin. It is estimated that 2.5 million pressure ulcers require treatment annually in the hospital setting, primarily targeting the elderly population, with total annual costs estimated at $2.2 to $3.6 billion. This does not include pain, suffering and other morbidities associated with pressure ulcers. Currently, there is no FDA approved therapy determined in randomized clinical trials for efficacy for pressure ulcers and no experimental model. Therefore, we aim to develop an experimental model to study changes that lead to development and impaired healing in pressure ulcers. In this proposal, we will use our Mechanical Explant Test System (METS) to compressively load (stress) human skin explants and determine time and load magnitude that generates pathogenic changes in the ECM, mechanical properties, cellular processes that will contribute to impaired wound healing and development of pressure ulcers. Furthermore, we will determine age related changes that will contribute to development of pressure ulcers using skin of young (25-35 years old), middle aged (40-55 years old) and elderly individuals (60-75 years old).The following parameters will be measured in skin specimens in the absence or presence of compressive load: 1) extra cellular matrix (ECM) properties (tenascin, fibronectin, elastin, procollagen, collagen, matrix metalloproteinases (MMP)) and its signaling (integrins, FAK and MAPK); 2) mechanical properties of the skin (tensile strength); 3) cellular morphology/biology (proliferation, apoptosis, and growth factor/cytokine production) using biomechanical testing and standard molecular biology techniques (immunohistochemistry, Western blots, real-time PCR). Our long-term goal is to eliminate stage IV pressure ulcers and decrease morbidity, mortality and suffering related to pressure ulcers among the elderly population. The experimental approach proposed in this application will provide us with the opportunity to identify changes that lead to pressure ulcers in elderly, an ultimate first step towards the development of novel therapeutic modalities. Developing an experimental model to study mechanisms that lead to bed sores (pressure ulcers) in elderly human skin is the first step towards identification of the cause (pathogenesis) of pressure ulcers. Currently, there is neither an adequate experimental model nor an FDA approved therapy for these ulcers, thus our research proposed will have a high impact in future development of potential therapy for treatment of this devastating disease. An experimental model for pressure ulcers will not only provide an understanding of the underlying mechanisms of pathogenesis, but also allow for pre- clinical testing of potential therapeutic modalities.