Integration properties of Wharton's jelly-derived novel mesenchymal stem cells into ventricular slices of murine hearts.

Wharton's jelly (WJ) is a rich source of multiple-lineage differentiating cells, recently proposed for cell replacement therapy. However, their ability to integrate into the cardiac tissue has not been elucidated, yet. We employed in vitro cardiac transplantation models to investigate the capacity of a novel population of human WJ-derived mesenchymal stem cells (nMSCs) to integrate into both living and ischemic cardiac tissue. NMSCs were characterized for the expression of stem/progenitor cell genes and proteins, as well as for multi-lineage differentiation potential. To assess their integration properties, nMSCs were cocultured with either living or ischemic embryonic murine ventricular slices. Immunohistochemical analyses were performed on cryosections of cocultured preparations to allow human cells tracking within the cocultures. Results showed that nMSCs shared MSC and endothelial colony-forming cell characteristics at gene, protein, and functional levels. NMSCs were markedly chemoattracted towards the ventricular slices, integrating robustly into the depth of both living and ischemic cardiac tissue. In conclusion, the functional ability of WJ-derived cells to populate the cardiac tissue could be validated in vitro. The transplantation models described could be further used to depict the mechanisms of WJ-derived cells integration into the cardiac tissue, contributing to optimization of reliable cell therapies for cardiac repair.

Direct contact of umbilical cord blood endothelial progenitors with living cardiac tissue is a requirement for vascular tube-like structures formation.

The umbilical cord blood derived endothelial progenitor cells (EPCs) contribute to vascular regeneration in experimental models of ischaemia. However, their ability to participate in cardiovascular tissue restoration has not been elucidated yet. We employed a novel coculture system to investigate whether human EPCs have the capacity to integrate into living and ischaemic cardiac tissue, and participate to neovascularization. EPCs were cocultured with either living or ischaemic murine embryonic ventricular slices, in the presence or absence of a pro-angiogenic growth factor cocktail consisting of VEGF, IGF-1, EGF and bFGF. Tracking of EPCs within the cocultures was performed by cell transfection with green fluorescent protein or by immunostaining performed with anti-human vWF, CD31, nuclei and mitochondria antibodies. EPCs generated vascular tube-like structures in direct contact with the living ventricular slices. Furthermore, the pro-angiogenic growth factor cocktail reduced significantly tubes formation. Coculture of EPCs with the living ventricular slices in a transwell system did not lead to vascular tube-like structures formation, demonstrating that the direct contact is necessary and that the soluble factors secreted by the living slices were not sufficient for their induction. No vascular tubes were formed when EPCs were cocultured with ischaemic ventricular slices, even in the presence of the pro-angiogenic cocktail. In conclusion, EPCs form vascular tube-like structures in contact with living cardiac tissue and the direct cell-to-cell interaction is a prerequisite for their induction. Understanding the cardiac niche and micro-environmental interactions that regulate EPCs integration and neovascularization are essential for applying these cells to cardiovascular regeneration.

Hematopoietic cell transplantation directly into dystrophic muscle fails to reconstitute satellite cells and myofibers.

We sought to determine whether wild-type hematopoietic cell transplantation directly into muscle could restore dystrophin expression in a relevant preclinical canine model of Duchenne muscular dystrophy. In recipients rendered tolerant to their dog leukocyte antigen-matched unaffected littermates through hematopoietic stem cell transplantation, intramuscular injection of donor marrow cells produced no evidence of dystrophin expression, and clonal analysis of satellite cells failed to reveal any donor contribution.

RDP58 does not prevent graft-versus-host disease after dog leukocyte antigen-nonidentical canine hematopoietic cell transplantation.

Graft-versus-host disease (GVHD) remains a cause of substantial morbidity for patients undergoing allogeneic hematopoietic cell transplantation (HCT). The present study was undertaken to investigate the effectiveness of RDP58, a peptide derived from the human leukocyte antigen class I heavy chain, in preventing GVHD in the established dog leukocyte antigen (DLA)-nonidentical canine model. Dogs underwent HCT from unrelated DLA-nonidentical donors after conditioning with 920 cGy total body irradiation. Engraftment and achievement of full donor chimerism was seen in five of six dogs, whereas one dog showed rejection and died of marrow aplasia. All five dogs with engraftment developed acute GVHD and were euthanized at an average of 20.6 days after HCT. Compared with historical controls, the Suse of RDP58 neither prevented acute GVHD nor significantly prolonged survival of DLA-nonidentical HCT recipients.

Use of multigeneration-family molecular dog leukocyte antigen typing to select a hematopoietic cell transplant donor for a dog with T-cell lymphoma.

CASE DESCRIPTION: A 7-year-old Golden Retriever was examined because of anorexia, lethargy, vomiting, and gradual weight loss. CLINICAL FINDINGS: Splenomegaly, pancytopenia, high serum calcium concentration, and high alkaline phosphatase activity were detected. Magnetic resonance imaging revealed an enlarged mesenteric lymph node and increased signals from the bone marrow of the ilium and vertebral bodies. Histologic examination and immunophenotyping of biopsy specimens confirmed a stage V (b) T-cell malignant lymphoma. TREATMENT AND OUTCOME: Clinical remission was attained by use of 2 chemotherapy cycles, followed by an allogeneic hematopoietic cell transplant performed at 18 weeks after diagnosis. A donor was identified by molecular dog leukocyte antigen typing methods. The patient was conditioned with 2 fractions of 4 Gy total body irradiation delivered 3 hours apart at 7 cGy/min, followed by an IV infusion of recombinant canine granulocyte colony-stimulating factor mobilized leukapheresis product and postgrafting immunosuppression with cyclosporine. Chimerism analyses revealed full donor engraftment that has been maintained for at least 58 weeks after transplant. Remission has been confirmed by normal results of serum thymidine kinase assays and the absence of peripheral blood clonal T-cell receptor gene rearrangements. CLINICAL RELEVANCE: Systemic chemotherapy induces remissions; however, most dogs succumb to disease recurrence because of multidrug resistance. Outcome of allogeneic hematopoietic cell transplantation in dogs can be excellent because of improved donor-recipient selection by use of molecular dog leukocyte antigen typing, compared with early attempts, and better prevention of graft versus host disease, better supportive care, and substitution of peripheral blood mononuclear cells for bone marrow.