Are macrophages involved in early myocardial reperfusion injury?

BACKGROUND: Neutrophils are the predominant phagocytes in the early stages of myocardial ischemia-reperfusion response and are also implicated in the development of tissue damage. This study examined the role of recruited macrophages in the evolution of this tissue injury. METHODS: Farm pigs were subjected to 30 minutes of myocardial ischemia followed by 30 minutes of reperfusion. Biopsy samples were taken from the control, ischemic, and ischemic-reperfused left ventricle wall and processed for both morphologic and biochemical analyses. In situ production of tumor necrosis factor-alpha was evaluated by Western blot and immunofluorescence. A full hemodynamic evaluation was also performed. RESULTS: Myocardial ischemia and early reperfusion caused marked neutrophil and macrophage tissue accumulation and tumor necrosis factor-alpha production by the injured tissue. Immunofluorescence studies allowed us to localize tumor necrosis factor-alpha predominantly in tissue-infiltrating macrophages. No depression in the global myocardial contractile function was observed, either during ischemia or after reperfusion. CONCLUSIONS: These data suggest that the newly recruited macrophages within the ischemic and early post-ischemic myocardium may play a role in promoting neutrophil tissue infiltration and subsequent neutrophil-induced tissue dysfunction by producing tumor necrosis factor-alpha.     

Sources of human hematopoietic stem cells for transplantation—a review

Transplantation of hematopoietic stem cells provides a means of replacing a defective hematopoietic system in patients with a wide range of malignant and nonmalignant disorders that affect the blood forming tissue. The same procedure has also allowed dose-escalation of standard chemotherapy and radiotherapy in the treatment of malignant disease of nonhematological origin. Until recently, bone marrow has been the sole source of hematopoietic stem cells, but limitations of conventional bone marrow transplantation have stimulated a search for alternative sources and uses of stem cells. Fetal tissues (especially liver) are a recognized source of transplantable stem cells and offer the great advantage of reduced immunogenicity, potentially removing the problems of tissue type matching. Umbilical cord blood is also a rich source of stem cells and, although it contains alloreactive cells, it is readily available without special ethical constraints. Both fetal tissue and cord blood suffer the disadvantages of limited numbers of stem cells per donation, and there is much interest in the development of technologies for the safe and reliable expansion and/or pooling of stem and progenitor cells. The observation that small numbers of stem cells are found in the peripheral blood of adults has led to the exploitation of the blood as a further source of stem cells. The ability to mobilize these cells from the medullary compartment into the periphery by the use of chemotherapy and/or recombinant hematopoietic growth factors has enabled the collection of sufficient numbers of cells for transplantation purposes. All of these advances are increasing the options and the range of choices available to clinicians and patients in the arena of hematopoietic stem cell transplantation.     

Do stem cells exist in the adult kidney?

Adult stem cells exist in many organs and play a critical role in normal cell turnover and the response to injury. The existence of adult stem cells in the mammalian kidney remains controversial. Kidney stem cells have been isolated and characterized by many groups, often with discrepant results. This article will review the current state of knowledge regarding adult kidney stem cells and discuss future directions for kidney stem cell research.     

Are OPG and RANKL involved in human fracture healing?

Human fracture healing is a complex interaction of several cytokines that regulate osteoblast and osteoclast activity. By monitoring OPG (osteoprotegerin) and sRANKL we aimed to possibly predict normal or impaired fracture healing. In 64 patients with a fracture of a long bone serum level of sRANKL and OPG were evaluated with respect to bony union (n = 57) or pseudarthrosis (n = 7). Measurements were carried out at admission and at 1, 2, 4, 6, 8, 12, 24, and 48 weeks after the injury. Patients' serum levels were compared to 33 healthy controls. Fracture hematoma contained significantly higher sRANKL and OPG concentrations compared to patients serum (p = 0.005, p = 0.028). OPG level in fracture hematoma was higher compared to the unions serum level (p = 0.028). sRANKL was decreased in unions during the observation period. In non‐unions sRANKL and OPG levels showed a variable course, with no statistical significance. This is the first study to document the course of OPG and sRANKL in normal and delayed human fracture healing emphasizing its local and systemic involvement. We provide evidence of strongly enhanced OPG levels in patients with a long bone fracture compared to healthy controls. Further, levels of free sRANKL were decreased during regular fracture repair. © 2014 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:1557–1561, 2014.     

Are tree squirrels involved in the circulation of flaviviruses in Italy?

West Nile virus (WNV ), Usutu virus (USUV ) and tick‐borne encephalitis virus (TBEV ) are emerging zoonotic flaviviruses (family Flaviviridae ), which have circulated in Europe in the past decade. A cross‐sectional study was conducted to assess exposure to these antigenically related flaviviruses in eastern grey squirrels (Sciurus carolinensis ) in Italy. Seventeen out of 158 (10.8%; CI _95%: 5.9‐15.6) squirrels’ sera tested through bELISA had antibodies against flaviviruses. Specific neutralizing antibodies to WNV , USUV and TBEV were detected by virus neutralization tests. Our results indicate that tree squirrels are exposed to Culex and tick‐borne zoonotic flaviviruses in Italy. Moreover, this study shows for the first time USUV and TBEV exposure in grey squirrels, broadening the host range reported for these viruses. Even though further studies are needed to define the real role of tree squirrels in the epidemiology of flaviviruses in Europe, this study highlights that serology could be an effective approach for future investigations aimed at broadening our knowledge about the species exposed to these zoonotic infections.     

Are CD34+ cells found in renal interstitial fibrosis?

BACKGROUND: The CD34 antigen is a marker of precursor myeloid cells and endothelial cells, but also of a subset of spindle cells. METHODS: To establish the possible role of CD34+ cells in the progression of glomerulonephritis, 30 renal biopsies were investigated. Immunohistochemistry for CD34 and smooth muscle actin (SMA) were performed by standard methods. The results were assessed semiquantitatively. The relative interstitial volume (RIV) was evaluated by the point counting method. Clinical data such as sex, age, serum creatinine and urea levels were taken into account. RESULTS: CD34+ spindle cells and SMA+ myofibroblasts were present in the renal interstitium in all but one case. In membranous, membranoproliferative and segmental-proliferative glomerulonephritis, CD34+ cells were seen in clusters, while in IgA nephropathy and in segmental and focal glomerulosclerosis, single, scattered cells were seen. The density of CD34+ cells showed a positive correlation with the myofibroblast density and the RIV. Serum creatinine and urea levels were associated with the RIV of the kidney and to a smaller degree with the number of myofibroblasts and CD34+ cells. CONCLUSION: These results show that in glomerulonephritis, CD34+ spindle cells appear in the interstitium. At present, their possible role can only be speculated.     

Collagen cross‐linking by adipose‐derived mesenchymal stromal cells and scar‐derived mesenchymal cells: Are mesenchymal stromal cells involved in scar formation?

In this work, different fibroblast-like (mesenchymal) cell populations that might be involved in wound healing were characterized and their involvement in scar formation was studied by determining collagen synthesis and processing. Depending on the physical and mechanical properties of the tissues, specific collagen cross-linking routes are followed. In skin the cross-linking of the pyridinium type is normally very low; however, in different forms of fibrosis increased levels of this type of cross-linking have been found. The enzyme lysyl hydroxylase-2b (LH-2b) plays a crucial role in this type of cross-linking. The gene expression levels of LH-2b, α-smooth muscle actin, and collagen types I and III were determined in dermis, subcutaneous fat, and (hypertrophic) scar tissue as well as in isolated cultured mesenchymal cells derived from these tissues, by real-time RT-polymerase chain reaction. Cultured mesenchymal cells from fat and scar tissue as well as the tissues itself showed significantly higher expression of LH-2b, α-SMA, and collagen type I than dermal mesenchymal cells. LH-2b-dependent pyridinium cross-linking was significantly enhanced in fat and scar tissue compared with dermis. FACS analysis was performed to characterize the fibroblast-like cells from the dermis, fat, and scar tissue. All cell populations express the distinct pattern of CD markers also expressed by mesenchymal stromal cells. Furthermore, parts of these cell populations were able to differentiate into adipocytes, chondrocytes, and osteoblasts. We conclude, therefore, that mesenchymal (stem) cells from the subcutaneous fat might be responsible for the accumulation of collagen in these scars.     

Are corneal cells susceptible to antibody-mediated killing in corneal allograft rejection?

PURPOSE: The precise role of antibodies in corneal transplantation is controversial. Clinical and experimental evidence both supports and refutes the contribution of donor-derived alloantibody in corneal allograft rejection. Accordingly, we prospectively evaluated the presence of donor-derived alloantibody in two high-risk donor-host combinations. We also evaluated the ability of this alloantibody to kill corneal epithelial, keratocytes, and endothelial cells in complement-dependent and complement-independent fashions. METHODS: C3H/Hej (H-2(k)) and Balb/c (H-2(d)) corneal grafts were transplanted orthotopically to CB6F1 (H-2(b/d)) and C57BL/6 (H-2(b)) recipients, respectively. These two donor-host combinations represent disparity at the entire MHC and multiple minor histocompatibility loci. Four objectives were addressed. First, we wished to determine if there was a correlation between the appearance of donor-specific serum IgG antibody and corneal graft rejection. Second, we evaluated the effect of passive transfer of hyperimmune donor-specific antibody on corneal allograft rejection. Third, we examined the capacity of donor-specific alloantibody to mediate complement-dependent cytolysis of corneal cells. Finally, we determined the capability of donor-specific alloantibody to mediate apoptosis of corneal cells. RESULTS: The presence of donor-specific serum IgG alloantibodies did not correlate with corneal graft rejection. One hundred percent of CB6F1 and C57BL/6 hosts rejected their C3H and Balb/c orthotopic corneal allografts, respectively. However, two of these seven CB6F1 hosts and one C57BL/6 host did not produce donor-specific IgG alloantibody that was significantly different from naive donors. Passive transfer of hyperimmune allo-antiserum prior to corneal transplantation did not increase the incidence, severity, or tempo of corneal allograft rejection in either donor-host combination. Hyperimmune allo-antiserum produced complement-mediated lysis of C3H corneal endothelial but not C3H corneal epithelial cells in the C3H-CB6F1 donor-host combination. Interestingly, all three corneal cell layers were vulnerable to complement-mediated cytolysis in the Balb/c-C57BL/6 donor-host combination. Additionally, Balb/c corneal epithelial, keratocytes, and endothelial cells were vulnerable to complement-independent, antibody induced apoptosis. CONCLUSIONS: Corneal graft rejection does not appear to correlate with the production of IgG alloantibody and can occur in the absence of donor-specific IgG alloantibody. Antibody-mediated killing of the corneal endothelium can occur in a complement-dependent or complement-independent fashion.     

The possible use of stem cells in regenerative medicine: dream or reality?

Stem cells are one of the most fascinating areas in regenerative medicine today. They play a crucial role in the development and regeneration of human life and are defined as cells that continuously reproduce themselves while maintaining the ability to differentiate into various cell types. Stem cells are found at all developmental stages, from embryonic stem cells that differentiate into all cell types found in the human body to adult stem cells that are responsible for tissue regeneration. The general opinion postulates that clinical therapies based on the properties of stem cells may have the potential to change the treatment of degenerative diseases or important traumatic injuries in the “near” future. We here briefly review the literature in particularly for the liver, heart, kidney, cartilage, and bone regeneration.     

The in vitro myelin formation in neurospheres of human neural stem cells

Objective: To explore the culture conditions of human neural stem cells and to investigate the ultrastructure of neurospheres. Methods: The cells from the embryonic human cortices were mechanically dissociated. N2 medium was adapted to culture and expand the cells. The cells were identified by immunocytochemistry and EM was applied to examine the ultrastructure of neurospheres. Results: The neural stem cells from human embryonic brains were successfully cultured and formed typical neurospheres in suspension, and most of the cells expressed vimentin, which was a marker for neural progenitor cells, and the cells could differentiate into neurons, astrocytes and oligodendrocytes. In vitro myelin formation in neurospheres were observed at an early stageof culture. Conclusions: Human neural stem cells can be cultured from embryonic brains, can form the typical neurospheres in suspension in vitro and have the ability of myelinating, and may be potential source for transplantation in treating myelin disorders.     

Co-infusion of donor adipose tissue-derived mesenchymal and hematopoietic stem cells helps safe minimization of immunosuppression in renal transplantation – single center experience

Background: Stem cell therapy (SCT) is used for immunosuppression minimization in renal transplantation (RT). We carried out a prospective study to evaluate the benefits of co-infusion of donor adipose-derived mesenchymal stem cells (AD-MSC) + hematopoietic stem cells (HSC) in living donor RT (LDRT) under non-myeloablative conditioning. Methods: In a demographically balanced three-armed LDRT trial with 95 patients in each arm, group-1 received portal co-infusion of AD-MSC + HSC, group-2 received HSC and group-3 received no SCT. Lymphoid irradiation and anti-thyroglobulin were used for conditioning. Results: SCT was safe. At 1 and 5 years post-transplant, patient survival was 100% and 94.7% in group-1, 100% and 95.7% in group-2, and 94.7% and 84% in group-3, death-censored graft survival was 100% and 94.6% in group-1, 100% and 91.3% in group-2, and 98.9% and 94.4% in group-3 with mean serum creatinine (mg/dL) of 1.38 and 1.39 in group-1, 1.48 and 1.51 in group-2, and 1.29 and 1.42 and in group-3. Rejection episodes and immunosuppression requirement were lesser in SCT groups versus controls with best results noted in group-1. Conclusion: Coinfusion of donor AD-MSC +HSC in portal circulation pre-transplant under non-myeloablative conditioning is safe and effective for immunosuppression minimization in LDRT.