Development of T lymphocytes at extrathymic sites.
(9/3936)
T lymphocytes expressing both CD4 and CD8 are the predominant cell type in the thymic cortex but are extremely rare outside the thymus of normal mice. In this article, we show that if precursor thymocytes (CD4-CD8-) from fetal or adult donors are injected i.v. into irradiated recipients, some of these cells will lodge in lymph nodes and develop into both CD4+CD8+ (double-positive) and CD4+ or CD8+ (single-positive) cells. This phenomenon also occurred in thymectomized recipients, strongly suggesting it is genuine extrathymic development. Prethymic precursors (e.g., fetal liver), were unable to use the lymph node for T cell development, without thymic processing. The data suggest that given unusual circumstances (irradiation or thymectomy and availability of appropriate precursors), the lymph nodes can support T cell development. (+info)
Evidence of long-term survival of donor-derived cells after limbal allograft transplantation.
(10/3936)
PURPOSE: Severe destruction of the corneal limbus causes conjunctival invasion and subsequent visual loss. Limbal allograft transplantation (LAT) was recently proposed for the treatment of these disorders. However, whether the method functions as a stem cell transplantation of the corneal epithelium remains unclear. This study provided evidence that donor-derived corneal epithelial cells survive long after LAT. METHODS: Epithelial cells on the paracentral cornea in patients who have undergone LAT were subjected to fluorescence in situ hybridization (FISH) and polymerase chain reaction restriction fragment length polymorphism (RFLP) analysis. X and Y chromosomes were detected using sex chromosome-specific probes in the FISH analysis, and HLA-DPBI antigens were examined in the RFLP analysis. Eyes receiving conventional penetrating keratoplasty (PKP) served as controls. RESULTS: Donor-derived epithelial cells were detected in three of five eyes (60.0%) in the FISH analysis and in seven of nine eyes (77.8%) in the RFLP analysis. Among these eyes, one and three eyes in the FISH and RFLP analysis, respectively, had both donor- and recipient-derived cells. In control PKP eyes, none of the eyes in the FISH analysis and one of eight eyes (12.5%) in the RFLP analysis had donor-derived cells. CONCLUSIONS: These results suggest that donor-derived cells survive much longer after LAT than those after PKP, and that LAT may function as stem cell transplantation of the corneal epithelium. (+info)
Embryonic stem cell-derived glial precursors: a source of myelinating transplants.
(11/3936)
Self-renewing, totipotent embryonic stem (ES) cells may provide a virtually unlimited donor source for transplantation. A protocol that permits the in vitro generation of precursors for oligodendrocytes and astrocytes from ES cells was devised. Transplantation in a rat model of a human myelin disease shows that these ES cell-derived precursors interact with host neurons and efficiently myelinate axons in brain and spinal cord. Thus, ES cells can serve as a valuable source of cell type-specific somatic precursors for neural transplantation. (+info)
Allo-limbal transplantation in patients with limbal stem cell deficiency.
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AIM: To report the outcome of a series of patients with stem cell deficiency who underwent allo-limbal transplantation and to describe a technique for this procedure. METHODS: Six consecutive patients underwent allo-limbal stem cell transplantation. The primary diagnosis included alkali burn (n = 2), trachoma (n = 1), chronic rosacea blepharitis and kerato-conjunctivitis (n = 1), aniridia (n = 1), and Stevens-Johnson syndrome (n = 1). The limbal rim consisted of peripheral cornea and perilimbal sclera. FK-506 was used postoperatively for immunosuppression. RESULTS: The length of follow up ranged from 3 to 24 months (mean follow up 11.8 (SD 9.3) months). The outcome was considered satisfactory in five of six cases. The corneal surface was completely epithelialised within 2 weeks, and there was a substantial improvement in vision and symptoms. One patient had recurrent epithelial defects related to eyelid abnormalities. No side effects associated with systemic immunosuppression were noted. CONCLUSION: Allo-limbal transplantation, with systemic immunosuppression with FK-506 is useful in reconstruction of the ocular surface with improvement in vision in patients with severe stem cell deficiency. (+info)
A mouse model of intestinal stem cell function and regeneration.
(13/3936)
We present here an in vivo mouse model for intestinal stem cell function and differentiation that uses postnatal intestinal epithelial cell aggregates to generate a differentiated murine small intestinal mucosa with full crypt-villus architecture. The process of neomucosal formation is highly similar to that of intestinal regeneration. Both in vivo grafting and primary culture of these cells reveal two different epithelial cell populations, which display properties consistent with intestinal epithelial transit amplifying and stem cell populations. Using this model system with a mixture of wild-type and transgene marked cells, we have shown that neomucosae originally develop from single aggregates, but that over time the mucosae fuse to form chimaeric mucosae. Despite fusion, the chimaeric mucosae maintain crypt clonality and villus polyclonality, demonstrating that clonal segregation persists during intestinal epithelial regeneration. (+info)
Myoblast transplantations lead to the expression of the laminin alpha 2 chain in normal and dystrophic (dy/dy) mouse muscles.
(14/3936)
Laminin-2 is part of the basement membrane of the skeletal muscle fibers. The laminin alpha 2 chain is absent or drastically reduced in a subgroup of congenital muscular dystrophy patients, and in the severely affected dystrophic dy/dy mouse. We previously reported that heterogeneous primary mouse muscle cell cultures conferred laminin alpha 2 chain expression in dy/dy mice muscles upon cell transplantation. In the present study we investigated whether pure myoblast cell lines were able to confer laminin alpha 2 chain expression in vivo. We observed that: (1) xeno-transplantation of non-immortalized human myoblast in SCID mouse muscles allows human laminin alpha 2 chain expression; (2) allotransplantation of the permanent G8 mouse myoblast cell line in dy/dy muscles allows the expression of the murine laminin alpha 2 chain; and (3) allo-transplantation of the D7 dystrophic dy/dy cell line allows the formation of new and hybrid muscle fibers in dy/dy muscle in the absence of laminin alpha 2 chain expression. We conclude that normal myoblasts are able to restore the expression of an extracellular skeletal muscle protein and that the absence of laminin-2 does not prevent transplanted muscle cells from participating in the formation of myofibers. Myoblasts are, therefore, attractive tools for further exploration of gene complementation strategies in the animal models of congenital muscular dystrophy. (+info)
Mobilisation of peripheral blood stem cells with IVE and G-CSF improves CD34+ cell yields and engraftment in patients with non-Hodgkin's lymphomas and Hodgkin's disease.
(15/3936)
The transplantation of mobilised peripheral blood stem cells is associated with more rapid engraftment than marrow transplantation. We have previously reported that G-IVE (G-CSF, ifosphamide, VP-16, epirubicin) improves the yield of CD34+ cells mobilised in patients with lymphoproliferative disorders compared with cyclophosphamide 3 g/m2 and G-CSF (G/CYCLO). In this study we have extended these observations to a larger series of patients including different lymphoma subtypes. Ninety-seven patients undergoing stem cell mobilisation were studied. Forty-two patients with lymphoproliferative disorders received G-IVE for mobilisation and 55 patients G/CYCLO. The median number of mobilised CD34+cells per leucapheresis was significantly higher for those patients receiving G-IVE: 5.82 x 106/kg (0.19-36) compared with 1.2 x 106/kg (0.04-17), P < 0.001 which resulted in a significantly reduced number of leucapheresis procedures performed in the G-IVE group. When patients were analysed dependent on underlying disease G-IVE mobilised significantly more CD34+cells per leucapheresis for all lymphoma types reaching 8.41 x 10(6)/kg (0.2-32) compared to 1.32 x 10(6)/kg (0. 06-17) for patients with high-grade NHL mobilised with G-IVE and C-GCSF respectively (P = 0.012). For patients with low-grade NHL 3. 12 x 10(6)/kg (0.10-24.39) compared to 1.08 x 10(6)/kg (0.04-9.74) were collected (P = 0.04) and for patients with Hodgkin's disease 3.02 x 10(6)/kg (1.48-36) and 1.04 x 10(6)/kg (0.1-12.3) (P = 0.001). Mobilisation with G-IVE resulted in the achievement of clinically significant CD34+ cell thresholds in a significantly higher proportion of patients compared to cyclophosphamide and G-CSF reaching >2.5 x 10(6)/kg CD34+ cells in 88% vs 62% (P = 0.004), >5 x 10(6)/kg in 67% vs18% (P = 0.001) and >10 x 10(6)/kg in 31% vs 14.5% (P = 0.05). Furthermore, an analysis of engraftment demonstrated that there was a significant reduction in the time to achieve platelet counts of >20 and >50 x 10(9)/l in patients receiving each incremental dose of CD34+ cells. We conclude that G-IVE mobilizes significantly more CD34+cells than G/CYCLO in patients with lymphoproliferative disorders. This effect is consistent in patients with high-grade NHL, low-grade NHL and HD and results in fewer failed stem collections and increased CD34+ cells available for transplantation which results in significantly accelerated platelet engraftment post transplant. (+info)
A novel model to study the dorsolateral migration of melanoblasts.
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Melanocytes derived from pluripotent neural crest cells migrate initially in the dorsolateral pathway between the ectoderm and dermomyotome. To understand the role of specific proteins involved in this cell migration, we looked for a cellular model that mimics the in vivo behavior of melanoblasts, and that allows functional studies of their migration. We report here that wild-type embryonic stem (ES) cells are able to follow the ventral and dorsolateral neural crest pathways after being grafted into chicken embryos. By contrast, a mutant ES cell line deficient for beta1 integrin subunits, proteins involved in cell-extracellular interactions, had a severely impaired migratory behavior. Interestingly, ES cells deficient for Kit, the tyrosine kinase receptor for the stem cell factor (SCF), behaved similarly to wild-type ES cells. Thus, grafting mouse ES cells into chicken embryos provides a new cellular system that allows both in vitro and in vivo studies of the molecular mechanisms controlling dorsolateral migration. (+info)