RESUMO
The field of stem cell therapeutics is moving ever closer to widespread application in the clinic. However, despite the undoubted potential held by these therapies, the balance between risk and benefit remains difficult to predict. As in any new field, a lack of previous application in man and gaps in the underlying science mean that regulators and investigators continue to look for a balance between minimizing potential risk and ensuring therapies are not needlessly kept from patients. Here, we attempt to identify the important safety issues, assessing the current advances in scientific knowledge and how they may translate to clinical therapeutic strategies in the identification and management of these risks. We also investigate the tools and techniques currently available to researchers during preclinical and clinical development of stem cell products, their utility and limitations, and how these tools may be strategically used in the development of these therapies. We conclude that ensuring safety through cutting-edge science and robust assays, coupled with regular and open discussions between regulators and academic/industrial investigators, is likely to prove the most fruitful route to ensuring the safest possible development of new products.
Assuntos
Terapia Baseada em Transplante de Células e Tecidos/métodos , Células-Tronco Pluripotentes/transplante , Transplante de Células-Tronco , Células-Tronco/citologia , Terapia Baseada em Transplante de Células e Tecidos/efeitos adversos , Humanos , Transplante AutólogoRESUMO
The transcriptional regulators of pluripotency, POU5F1 (OCT4), NANOG and SOX2, are highly expressed in embryonal carcinoma (EC). In contrast to OCT4 and NANOG, SOX2 has not been demonstrated in the early human germ cell lineage or carcinoma in situ (CIS), the precursor for testicular germ cell tumours (TGCTs). Here, we have analysed SOX2 expression in CIS and overt TGCTs, as well as normal second and third trimester fetal, prepubertal and adult testes by in situ hybridisation and immunohistochemistry using three different antibodies. In contrast to earlier studies, we detected SOX2 mRNA in most CIS cells. We also detected speckled nuclear SOX2 immunoreactivity in CIS cells with one primary antibody, which was not apparent with other primary antibodies. The results demonstrate SOX2 gene expression in CIS for the first time and raise the possibility of post-transcriptional regulation, most likely sumoylation as a mechanism for limiting SOX2 action in these cells.
Assuntos
Células Germinativas/metabolismo , Neoplasias Embrionárias de Células Germinativas/metabolismo , Fatores de Transcrição SOXB1/metabolismo , Neoplasias Testiculares/metabolismo , Testículo/metabolismo , Adulto , Carcinoma Embrionário/genética , Carcinoma Embrionário/metabolismo , Linhagem Celular , Expressão Gênica , Genes , Células Germinativas/química , Humanos , Imuno-Histoquímica , Masculino , Neoplasias Embrionárias de Células Germinativas/genética , RNA Mensageiro/metabolismo , Fatores de Transcrição SOXB1/genética , Testículo/químicaRESUMO
Human marrow stromal cells (MSCs) can be isolated from bone marrow and differentiate into multiple tissues in vitro and in vivo. These properties make them promising tools in cell and gene therapy. The lack of a specific MSC marker and the low frequency of MSCs in bone marrow necessitate their isolation by in vitro expansion prior to clinical use. This may severely reduce MSC proliferative capacity to the point that the residual proliferative potential is insufficient to maintain long-term tissue regeneration upon reinfusion. In this study we determined the effect of in vitro expansion on the replicative capacity of MSCs by correlating their rate of telomere loss during in vitro expansion with their behavior in vivo. We report that even protocols that involve minimal expansion induce a rapid aging of MSCs, with losses equivalent to about half their total replicative lifespan.
Assuntos
Células da Medula Óssea/metabolismo , Divisão Celular/genética , Senescência Celular/genética , Células-Tronco Mesenquimais/metabolismo , Telômero/genética , Técnicas de Cultura de Células/métodos , Diferenciação Celular/genética , Células Cultivadas , Humanos , Cinética , Longevidade/genética , Transplante de Células-Tronco Mesenquimais/métodos , Osteócitos/metabolismo , Osteogênese/genética , Células Estromais/metabolismoRESUMO
We have investigated the utility of bone marrow-derived mesenchymal stem cells (MSCs) as targets for gene therapy of the autosomal recessive disorder mucopolysaccharidosis type IH (MPS-IH, Hurler syndrome). Cultures of MSCs were initially exposed to a green fluorescent protein-expressing retrovirus. Green fluorescent protein-positive cells maintained their proliferative and differentiation capacity. Next we used a vector encoding alpha-L-iduronidase (IDUA), the enzyme that is defective in MPS-IH. Following transduction, MPS-IH MSCs expressed high levels of IDUA and secreted supernormal levels of this enzyme into the extracellular medium. Exogenous IDUA expression led to a normalization of glycosaminoglycan storage in MPS-IH cells, as evidenced by a dramatic decrease in the amount of (35)SO(4) sequestered within the heparan sulfate and dermatan sulfate compartments of these cells. Finally, gene-modified MSCs were able to cross-correct the enzyme defect in untransduced MPS-IH fibroblasts via protein transfer.