[Joseph Eustache Crocé-Spinelli] / Pierre Petit

Donateur : Tissandier, Gaston (1843-1899)

Estimating dormant and active hematopoietic stem cell kinetics through extensive modeling of bromodeoxyuridine label-retaining cell dynamics.

Bone marrow hematopoietic stem cells (HSCs) are responsible for both lifelong daily maintenance of all blood cells and for repair after cell loss. Until recently the cellular mechanisms by which HSCs accomplish these two very different tasks remained an open question. Biological evidence has now been found for the existence of two related mouse HSC populations. First, a dormant HSC (d-HSC) population which harbors the highest self-renewal potential of all blood cells but is only induced into active self-renewal in response to hematopoietic stress. And second, an active HSC (a-HSC) subset that by and large produces the progenitors and mature cells required for maintenance of day-to-day hematopoiesis. Here we present computational analyses further supporting the d-HSC concept through extensive modeling of experimental DNA label-retaining cell (LRC) data. Our conclusion that the presence of a slowly dividing subpopulation of HSCs is the most likely explanation (amongst the various possible causes including stochastic cellular variation) of the observed long term Bromodeoxyuridine (BrdU) retention, is confirmed by the deterministic and stochastic models presented here. Moreover, modeling both HSC BrdU uptake and dilution in three stages and careful treatment of the BrdU detection sensitivity permitted improved estimates of HSC turnover rates. This analysis predicts that d-HSCs cycle about once every 149-193 days and a-HSCs about once every 28-36 days. We further predict that, using LRC assays, a 75%-92.5% purification of d-HSCs can be achieved after 59-130 days of chase. Interestingly, the d-HSC proportion is now estimated to be around 30-45% of total HSCs - more than twice that of our previous estimate.

[Illustrations de La Gloire du Val-de-Grâce] / Pierre Mignard, dess. ; François Chauveau, grav.

Comprend : [Fig. à la Page de Titre : cartouche avec devise, ange et soldat.] In Hoc Signo Vinces. [Cote : Ye 669/Microfilm R 122335] ; [Fronstispice après la Page de Titre : Le Parnasse, Apolllon et les Muses.] [Cote : Ye 669/Microfilm R 122335] ; [Bandeau et lettre historiée folio Aiij : putti dessinant, travaillant la peinture, le modelage, la géométrie et la perspective. La reine Marie de Médicis offrant à Dieu la construction du Val-de-Grâce.] [Cote : Ye 669/Microfilm R 122335] ; [Fig. p.26 : allégories du Temps, de la Mort et de la Peinture (ou Postérité?), putti.] [Cote : Ye 669/Microfilm R 122335]