脂肪细胞是干细胞的已知来源。它们很容易收获,并且是自体移植物的合适候选者。脂肪来源的干细胞(ADSCs)有多个可以分化的靶组织,包括骨和软骨.在脂肪组织中,ADSCs能够分化,以及提供能量和细胞因子/激素的供应来管理低氧和脂质/激素饱和的脂肪环境。纤溶酶原激活系统(PAS)控制脂肪和伤口愈合环境中的大多数蛋白水解活性,允许快速的细胞迁移和组织重塑。虽然PAS的主要激活途径是通过尿激酶纤溶酶原激活剂(uPA)发生的,内皮细胞高度表达,其功能不仅限于实现血运重建。蛋白水解活性依赖于蛋白酶的活化,本地化,回收机制和底物可用性。uPA和uPA激活的纤溶酶原允许多能细胞到达新的局部环境并满足生态位需求。然而,过度刺激,获得迁移表型和恒定的蛋白质周转可能不利于结构化硬组织和软组织的形成。为了保持合适的愈合模式,uPA刺激的蛋白水解活性受到纤溶酶原激活剂抑制剂1的调节。根据生理设置,重塑机制的不同部分被激活,结果各不相同。利用每个微环境内的差异来重建所需的生态位是一种有效的治疗性生物工程方法。通过控制与接受性干细胞谱系结合的蛋白质更新速率,例如ADSC,可能会发现一条关于治疗机会的新途径,可以克服局限性,比如干细胞的稀缺,血管生成潜力低或宿主组织适应性差。
Adipocytes are a known source of stem cells. They are easy to harvest, and are a suitable candidate for autogenous grafts. Adipose derived stem cells (ADSCs) have multiple target tissues which they can differentiate into, including bone and cartilage. In adipose tissue, ADSCs are able to differentiate, as well as providing energy and a supply of cytokines/hormones to manage the hypoxic and lipid/hormone saturated adipose environment. The plasminogen activation system (PAS) controls the majority of proteolytic activities in both adipose and wound healing environments, allowing for rapid cellular migration and tissue remodelling. While the primary activation pathway for PAS occurs through the urokinase plasminogen activator (
uPA), which is highly expressed by endothelial cells, its function is not limited to enabling revascularisation. Proteolytic activity is dependent on protease activation, localisation, recycling mechanisms and substrate availability.
uPA and
uPA activated plasminogen allows pluripotent cells to arrive to new local environments and fulfil the niche demands. However, overstimulation, the acquisition of a migratory phenotype and constant protein turnover can be unconducive to the formation of structured hard and soft tissues. To maintain a suitable healing pattern, the proteolytic activity stimulated by
uPA is modulated by plasminogen activator inhibitor 1. Depending on the physiological settings, different parts of the remodelling mechanism are activated with varying results. Utilising the differences within each microenvironment to recreate a desired niche is a valid therapeutic bio-engineering approach. By controlling the rate of protein turnover combined with a receptive stem cell lineage, such as ADSC, a novel avenue on the therapeutic opportunities may be identified, which can overcome limitations, such as scarcity of stem cells, low angiogenic potential or poor host tissue adaptation.