In vitro expansion of hematopoietic stem cells by recombinant TAT-HOXB4 protein.
Hematopoietic stem cells (HSCs) can self-renew extensively after transplantation. The conditions supporting their in vitro expansion are still being defined. Retroviral overexpression of the human homeobox B4 (HOXB4) gene in mouse bone marrow cells enables over 40-fold expansion of HSCs in vitro. To circumvent the requirement for retroviral infection, we used recombinant human TAT-HOXB4 protein carrying the protein transduction domain of the HIV transactivating protein (TAT) as a potential growth factor for stem cells. HSCs exposed to TAT-HOXB4 for 4 d expanded by about four- to sixfold and were 8-20 times more numerous than HSCs in control cultures, indicating that HSC expansion induced by TAT-HOXB4 was comparable to that induced by the human HOXB4 retrovirus during a similar period of observation. Our results also show that TAT-HOXB4-expanded HSC populations retain their normal in vivo potential for differentiation and long-term repopulation. It is thus feasible to exploit recombinant HOXB4 protein for rapid and significant ex vivo expansion of normal HSCs.
Laboratory of Molecular Genetics of Hemopoietic Stem Cells, Clinical Research Institute of Montreal, Montreal, Quebec, Canada, H2W 1R7.
Jana
J
Krosl
Pamela
P
Austin
Nathalie
N
Beslu
Evert
E
Kroon
R Keith
RK
Humphries
Guy
G
Sauvageau
D000818:Animals; D002455:Cell Division / Q000502:physiology*; D015696:Gene Products, tat / Q000235:genetics* / Q000378:metabolism; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D012190:Retroviridae; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D015696:Gene Products, tat; C090460:HOXB4 protein, human; D018398:Homeodomain Proteins; C513262:Hoxb4 protein, mouse; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors