In rodents, bone marrow-derived cells enter the brain during adult life. Allogeneic bone marrow transplantation is used to treat genetic CNS diseases, but the fate of human bone marrow and CD34 ؉ cells within the brain remains to be elucidated. The present study demonstrates that cells derived from human CD34 ؉ cells, isolated from either cord blood or peripheral blood, migrate into the brain after infusion into nonobese diabetic͞severe combined immunodeficient mice. Both types of CD34 ؉ -derived cells differentiate into perivascular and ramified microglia. The lentiviral transfer of genes into CD34 ؉ cells before infusion does not modify the differentiation of human CD34 ؉ cells into microglia, allowing new transgenic proteins to be expressed in these cells. The transplantation of CD34 ؉ cells could thus be used for the treatment of CNS diseases. U p to 20% of the total nonneuronal cell population is made of microglia (1). Microglia are ubiquitously distributed in the CNS and play a major role in the response to infectious, traumatic, inflammatory, and ischemic processes, as well as in degenerative CNS diseases, such as Alzheimer's disease, multiple sclerosis, or Parkinson's disease. The adult brain contains two subsets of microglia: the resting microglia, which ramify throughout the brain parenchyma, and the perivascular microglia, which resemble peripheral macrophages (1, 2).Following a long debate about their origin, microglia are now believed to be derived from bone marrow as liver, spleen, or lung macrophages (2). Murine bone marrow-derived cells enter the CNS and differentiate into microglia (3-5). In mice, the turnover of perivascular microglia reaches 30% 1 year after engraftment, whereas the turnover of ramified microglia is much slower (6, 7). However, the subset of bone marrow-derived cells that are the progenitors of microglia has not been characterized. In mice, transplantation of transduced bone marrow cells allows the expression of glucocerebrosidase or GFP in microglia (8, 9). In humans, there are very little data documenting the fate of bone marrow-derived cells in the CNS after bone marrow transplantation (BMT) (10, 11). However, that BMT is used to treat genetic CNS diseases like Hurler disease or X-linked adrenoleukodystrophy (ALD) (12, 13) suggests that bone marrow cells may serve as vehicles for the delivery of genes into the human CNS.Transplantation of CD34 ϩ hematopoietic cells is replacing that of whole bone marrow cells for many applications, including autotransplantation in cancer, non-HLA genoidentical BMT, and gene therapy (14-16). Human CD34 ϩ cells can be easily collected from cord blood at birth or from peripheral blood after cytokine mobilization. We studied the migration, differentiation, and distribution of human CD34 ϩ cells purified either from umbilical cord blood (UCB) or from mobilized peripheral blood (MPB) in the brain of nonobese diabetic͞severe combined immunodeficient (NOD͞SCID) mouse. Our results demonstrate that a fraction of these cells, when infused into NOD͞SCI...

Indocyanine green clearance (Cl-ICG) has been used to assess liver function and hepatic blood flow mainly before and after hepatic surgery. Cl-ICG (invasive method) has been reported to be a good marker of early graft function after liver transplantation (LT). The goal of this study was to determine if the indocyanine green plasma disappearance rate (PDR-ICG), measured by a noninvasive technique (LiMON, Impulse Medical System, Munich, Germany), is predictive of complications and graft outcome after LT. From September 2005 to June 2006, 72 LT recipients were included in the study. PDR-ICG was measured daily (from day 0 to day 5 after LT) with a digital sensor after patients were injected with 0.25 mg/kg indocyanine green. A PDR-ICG cutoff level of 12.85%/minute was predictive of the development of a serious postoperative complication. The sequential changes of PDR-ICG enabled us to differentiate 2 groups: (1) patients with early severe complications (hepatic artery thrombosis, primary graft nonfunction, or sepsis) who had a low value of PDR-ICG during the first 5 posttransplantation days (average, 8.8 Ϯ 4.5%/minute) and (2) patients who developed acute rejection and who had a progressive reduction of PDR-ICG between days 0 and 5 (from 25.5 Ϯ 4.8 to 10.3 Ϯ 2.5%/minute; P Ͻ 0.002). In conclusion, after LT, PDR-ICG (a noninvasive technique), measured regularly during the first 5 postoperative days, is a safe technique that can predict early postoperative complications.