Muscle regeneration through stem cell transplantation

描述（由申请人提供）： 最近，我们利用一种改良的预平板技术，从正常小鼠骨骼肌中分离出3个肌源性细胞群，基于它们的粘附特性和增殖行为。其中2个细胞群具有卫星细胞特征，而第3个细胞群由表达造血干细胞标志物的长期增殖（LTP）细胞组成。 LTP细胞的干细胞特征包括在培养物中保持其表型超过30代（自我更新）和分化成各种谱系（包括肌肉、神经、成骨和内皮）的能力。 与卫星细胞移植相比，LTP细胞的移植显著提高了肌肉再生和肌营养不良蛋白递送至营养不良肌肉的效率。 我们提出的项目的总体目标是进一步研究LTP细胞的重要特征（即，来源和机制与改善的移植能力有关），这对于它们在移植中改善肌肉再生和将肌营养不良蛋白递送到营养不良的肌肉的潜在用途是至关重要的。在本项目中，我们将通过确定LTP细胞与卫星细胞和来自骨骼肌的侧群（SP）干细胞的关系来研究LTP细胞的潜在来源（目标#1）。随后，我们将研究LTP细胞在骨骼肌中显示出改善的移植能力的机制。我们将评估细胞增殖和分化动力学的相对影响（目标#2），并确定免疫特权细胞行为在骨骼肌中LTP细胞再生能力增加中也起作用的可能性（目标#3）。 对LTP细胞自我更新和多能能力的相对重要性的分析将阐明干细胞特性对骨骼肌中改善的移植能力的贡献（目标#4）。 这个项目可能会增加我们对显示干细胞特征的肌源性细胞群的基本生物学的理解。 这反过来又可能揭示新的技术，以改善肌肉再生营养不良或受伤的骨骼肌通过移植肌肉来源的干细胞。

DESCRIPTION (provided by applicant): We recently have used a modified preplate technique to isolate 3 populations of myogenic cells from normal mouse skeletal muscle based on their adhesion characteristics and proliferation behaviors. Although 2 of these populations display satellite cell characteristics, the third population consists of long_term proliferating (LTP) cells expressing hematopoietic stem cell markers. The stem cell characteristics of the LTP cells include the abilities to retain their phenotype for more than 30 passages in culture (self-renewal) and to differentiate into various lineages, including muscle, neural, osteogenic, and endothelial. The transplantation of the LTP cells, in contrast to satellite cell transplantation, significantly improved the efficiency of muscle regeneration and dystrophin delivery to dystrophic muscle. The overall goal of our proposed project is to further investigate important features of the LTP cells (i.e., sources and mechanisms involved with the improved transplantation capacity) that are paramount to their potential use in transplantation to improve muscle regeneration and deliver dystrophin to dystrophic muscle. In this project we will investigate potential sources of the LTP cells by determining their relationship to satellite cells and to the Side Population (SP) stem cells derived from skeletal muscle (Aim #1). We subsequently will investigate mechanisms by which the LTP cells display an improved transplantation capacity in skeletal muscle. We will evaluate the relative effects of the proliferation and differentiation kinetics of the cells (Aim #2) and determine the possibility that immune_privileged cell behavior also plays a role in the increased regenerative capacity of LTP cells in skeletal muscle (Aim #3). Analysis of the relative importance of the LTP cells' self-renewal and multipotent capabilities will shed light on the contribution of stem cell characteristics to the improved transplantation capacity in skeletal muscle (Aim #4). This project might increase our understanding of the basic biology of myogenic cell populations that display stem cell characteristics. This in turn may unveil new techniques to improve muscle regeneration in dystrophic or injured skeletal muscle via the transplantation of muscle-derived stem cells.