Homing of lin−/CD117+ hematopoietic stem cells

Epidermal Growth Factor Attenuates Delayed Ionizing Radiation-Induced Tissue Damage in Bone Marrow Transplanted Mice

We examined the effect of epidermal growth factor (EGF) treatment in mice that received bone marrow transplantation (BMT) after 11 Gy whole-body irradiation. C57Bl/6 mice were divided into three treatment groups: 0 Gy; 11 Gy ((60)Co, single dose, 0.51 Gy/min) with BMT (5 × 10(6) bone marrow cells isolated from green fluorescent protein syngeneic mice, 3-4 h postirradiation); and 11 Gy with BMT and EGF (2 mg/kg applied subcutaneously 1, 3 and 5 days postirradiation). Survival data were collected. Bone marrow, peripheral blood count and cytokines, gastrointestine and liver parameters and migration of green fluorescent protein-positive cells were evaluated at 63 days postirradiation. Epidermal growth factor increased survival of irradiated animals that received BMT from 10.7 to 85.7% at 180 days postirradiation. In the BMT group, we found changes in differential bone marrow and blood count, plasma cytokine levels, gastrointestinal tissues and liver at 63 days postirradiation. These alterations were completely or in some parameters at least partially restored by epidermal growth factor. These findings indicate that epidermal growth factor, administered 1, 3 and 5 days postirradiation in combination with bone marrow transplantation, significantly improves long-term prognosis.

Hematopoietic stem cell transplantation for multiple sclerosis: is it a clinical reality?

Hematopoietic stem cell transplantation (HSCT) is a treatment paradigm that has long been utilized for cancers of the blood and bone marrow but has gained some traction as a treatment paradigm for multiple sclerosis (MS). Success in the treatment of patients with this approach has been reported primarily when strict inclusion criteria are imposed that have eventuated a more precise understanding of MS pathophysiology, thereby governing trial design. Moreover, enhancing the yield and purity of hematopoietic stem cells during isolation along with the utility of appropriate conditioning agents has provided a clearer foundation for clinical translation studies. To support this approach, preclinical data derived from animal models of MS, experimental autoimmune encephalomyelitis, have provided clear identification of multipotent stem cells that can reconstitute the immune system to override the autoimmune attack of the central nervous system. In this review, we will discuss the rationale of HSCT to treat MS by providing the benefits and complications of the clinically relevant protocols, the varying graft types, and conditioning regimens. However, we emphasize that future trials based on HSCT should be focused on specific therapeutic strategies to target and limit ongoing neurodegeneration and demyelination in progressive MS, in the hope that such treatment may serve a greater catchment of patient cohorts with potentially enhanced efficiency and lower toxicity. Despite these future ambitions, a proposed international multicenter, randomized clinical trial of HSCT should be governed by the best standard care of treatment, whereby MS patients are selected upon strict clinical course criteria and long-term follow-up studies of patients from international registries are imposed to advocate HSCT as a therapeutic option in the management of MS.

Attenuation of radiation-induced gastrointestinal damage by epidermal growth factor and bone marrow transplantation in mice

PURPOSE

We examined the effect of epidermal growth factor (EGF) and bone marrow transplantation (BMT) on gastrointestinal damage after high-dose irradiation of mice.

MATERIAL AND METHODS

C57Black/6 mice were used. Two survival experiments were performed (12 and 13 Gy; (60)Co, 0.59-0.57 Gy/min). To evaluate BMT and EGF action, five groups were established - 0 Gy, 13 Gy, 13 Gy + EGF (at 2 mg/kg, first dose 24 h after irradiation and then every 48 h), 13 Gy + BMT (5 × 10(6) cells from green fluorescent protein [GFP] syngenic mice, 4 h after irradiation), and 13 Gy + BMT + EGF. Survival data, blood cell counts, gastrointestine and liver parameters and GFP positive cell migration were measured.

RESULTS

BMT and EGF (three doses, at 2 mg/kg, administered 1, 3 and 5 days after irradiation) significantly increased survival (13 Gy). In blood, progressive cytopenia was observed with BMT, EGF or their combination having no improving effect early after irradiation. In gastrointestinal system, BMT, EGF and their combination attenuated radiation-induced atrophy and increased regeneration during first week after irradiation with the combination being most effective. Signs of systemic inflammatory reaction were observed 30 days after irradiation.

CONCLUSIONS

Our data indicate that BMT together with EGF is a promising strategy in the treatment of high-dose whole-body irradiation damage.

A patient tumor-derived orthotopic xenograft mouse model replicating the group 3 supratentorial primitive neuroectodermal tumor in children

BACKGROUND

Supratentorial primitive neuroectodermal tumor (sPNET) is a malignant brain tumor with poor prognosis. New model systems that replicate sPNET's molecular subtype(s) and maintain cancer stem cell (CSC) pool are needed.

METHODS

A fresh surgical specimen of a pediatric sPNET was directly injected into the right cerebrum of Rag2/SCID mice. The xenograft tumors were serially sub-transplanted in mouse brains, characterized histopathologically, and subclassified into molecular subtype through qRT-PCR and immunohistochemical analysis. CSCs were identified through flow cytometric profiling of putative CSC markers (CD133, CD15, CD24, CD44, and CD117), functional examination of neurosphere forming efficiency in vitro, and tumor formation capacity in vivo. To establish a neurosphere line, neurospheres were propagated in serum-free medium.

RESULTS

Formation of intracerebral xenograft tumors was confirmed in 4 of the 5 mice injected with the patient tumor. These xenograft tumors were sub-transplanted in vivo 5 times. They replicated the histopathological features of the original patient tumor and expressed the molecular markers (TWIST1 and FOXJ1) of group 3 sPNET. CD133(+) and CD15(+) cells were found to have strong neurosphere-forming efficiency in vitro and potent tumor-forming capacity (with as few as 100 cells) in vivo. A neurosphere line BXD-2664PNET-NS was established that preserved stem cell features and expressed group 3 markers.

CONCLUSION

We have established a group 3 sPNET xenograft mouse model (IC-2664PNET) with matching neurosphere line (BXD-2664PNET-NS) and identified CD133(+) and CD15(+) cells as the major CSC subpopulations. This novel model system should facilitate biological studies and preclinical drug screenings for childhood sPNET.

The peripheral chimerism of bone marrow-derived stem cells after transplantation: regeneration of gastrointestinal tissues in lethally irradiated mice

Bone marrow–derived cells represent a heterogeneous cell population containing haematopoietic stem and progenitor cells. These cells have been identified as potential candidates for use in cell therapy for the regeneration of damaged tissues caused by trauma, degenerative diseases, ischaemia and inflammation or cancer treatment. In our study, we examined a model using whole-body irradiation and the transplantation of bone marrow (BM) or haematopoietic stem cells (HSCs) to study the repair of haematopoiesis, extramedullary haematopoiesis and the migration of green fluorescent protein (GFP⁺) transplanted cells into non-haematopoietic tissues. We investigated the repair of damage to the BM, peripheral blood, spleen and thymus and assessed the ability of this treatment to induce the entry of BM cells or GFP⁺lin⁻Sca-1⁺ cells into non-haematopoietic tissues. The transplantation of BM cells or GFP⁺lin⁻Sca-1⁺ cells from GFP transgenic mice successfully repopulated haematopoiesis and the haematopoietic niche in haematopoietic tissues, specifically the BM, spleen and thymus. The transplanted GFP⁺ cells also entered the gastrointestinal tract (GIT) following whole-body irradiation. Our results demonstrate that whole-body irradiation does not significantly alter the integrity of tissues such as those in the small intestine and liver. Whole-body irradiation also induced myeloablation and chimerism in tissues, and induced the entry of transplanted cells into the small intestine and liver. This result demonstrates that grafted BM cells or GFP⁺lin⁻Sca-1⁺ cells are not transient in the GIT. Thus, these transplanted cells could be used for the long-term treatment of various pathologies or as a one-time treatment option if myeloablation-induced chimerism alone is not sufficient to induce the entry of transplanted cells into non-haematopoietic tissues.

Splenectomy influences homing of transplanted stem cells in bone marrow-ablated mice

Cell mobilization, a process that influences circulation, margination, and finally, homing play key roles in the regeneration processes mediated by stem cells. Recent studies as well as prior studies from our group indicate an important role of the spleen in hematopoietic reconstitution, but to date the role of the spleen in hematopoietic reconstitution has been unclear and it has not been precisely documented in ablated animals. Therefore, we undertook the present study to define more closely the role of the spleen in hematopoietic reconstitution in lethally irradiated mice. After transplantation of irradiated mice with lacZ+ -marked lin- / CD117+ bone marrow cells, we compared splenectomized mice (T(S), splenectomy performed prior to irradiation) to nonsplenectomized, irradiated mice (T(N)) as well as to normal (unirradiated) mice. Impaired hematopoietic reconstitution was observed in T(S) mice. Splenectomy markedly altered the distribution of hematopoietic stem cells, as demonstrated by fluorescence-activated cell sorting analysis of endogenous CD117+ cells in the thymus and bone marrow of recipients. Cell engraftment was demonstrated by histochemical and polymerase chain reaction analyses of recipient tissues. These experiments demonstrated that in T(S) animals, transplanted hematopoietic stem cells mobilized to extravascular tissues, particularly the gastrointestinal tract. The number of donor cells in recipient tissues continued to increase for 30 days after transplantation with the highest numbers observed in the T(S) group. DNA marking analysis led to the conclusion that engrafted cells were not only integrated into recipient tissues but were also capable of performing complex cellular processes, including proliferation and repair. Our results are consistent with the novel possibility that cellular repair markedly affects stem cell regenerative functions and that repair is markedly influenced by the integrity and presence of organs not directly involved in specific tissue regeneration processes, particularly the spleen.