Mouse hematopoietic stem cell (HSC) transplantation is a well-established in vivo model system to study various factors affecting normal and pathologic blood cell development. Based on the currently accepted classification primitive HSCs are multipotent adult stem cells that can be divided developmentally into two different stages: long-term HSCs and short-term HSCs (1). However, bone marrow contains largely heterogeneous and functionally distinct subpopulations of hematopoietic stem and progenitor cells separated by their self-renewal ability, clone size, differentiation capacity, migration patterns, and primitiveness (2). Due to this variability the reproducible isolation of HSCs representing biologically homogenous population is a very difficult task. Therefore, the characterization of HSCs is based on the in vitro functional assays, such as methylcellulose colony forming assay, or in vivo studies like competitive repopulation unit assay and the ability to form hematopoietic chimera after transplantation.
Gene Therapy Technology
Experimental hind limb injury is widely used to study the effect of transgenes, stem cells, or pharmaceuticals on e.g. new vessel formation (1,2,3,4). The degree of the injury depends on the number and the location of the vessels ligated, therefore having an impact on the recovery process and the monitoring of the transgene response. Even though terminally differentiated myofibers are not able to proliferate the skeletal muscle has a remarkable regenerative potential, which is thought to be due to the satellite cell differentiation as response to injury (5,6). Selection of the species between mouse, rat, and rabbit depends on the purpose of the study and has an impact on the method of vessel ligation. In the current review we focus on to describe the hind limb injury execution in a rat model.
The recent developments of viral based vectors in design, in biosafety and in accomplishing high transfection efficiency for transgene expression into target cells makes them attractive tool for various gene transfer applications. Several kinds of viruses, including HIV derived Lentivirus vectors (LVs), non-HIV based Retroviruses, Adenoviruses, Adeno-associated viruses, Baculovirus and Herpes simplex viruses have been manipulated for use in gene transfer and gene therapy purposes. Each viral vector system is integrated with a distinctive in built properties that affect its suitability for specific gene therapy purposes. Although LVs offered many unique solutions for advanced gene therapy research and clinical applications, however, several important issues of LVs gene therapy must be overcome before it gains widespread use. Nonetheless, the number of promising gene therapy studies in progress are highly encouraging and outcome from these clinical trials will provide valuable insights particularly for the clinical suitability and safety profile of LVs. This review contain a comprehensive discussion starting with the general background of the field thereafter discussing the salient features of recent developments in viral vector system in general and with special focus on LVs.