RESUMO
The general opinion that hemoglobin is only a carrier protein for oxygen and carbon dioxide has been challenged by several recent studies showing hemoglobin expression in other cells than those of the erythroid series, for example, in macrophages. We discovered ß-globin expression in rat experimental granulation tissue induced by subcutaneously implanted cellulose sponges. Closer investigation revealed also α-globin expression. The first peak of the biphasic globin expression noticed during granulation tissue formation correlated with the invasion of monocytes/macrophages, whereas the second one seemed to be connected to the appearance of hematopoietic progenitors. Data presented in this study indicate globin expression both in macrophages and in immature erythroid cells as validated by erythroid-specific markers.
Assuntos
Regulação da Expressão Gênica , Tecido de Granulação/metabolismo , Hemoglobinas/metabolismo , Animais , Células Eritroides/metabolismo , Eritropoese/genética , Perfilação da Expressão Gênica , Hemoglobinas/genética , Macrófagos/metabolismo , Masculino , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , alfa-Globinas/genética , alfa-Globinas/metabolismo , Globinas beta/genética , Globinas beta/metabolismoRESUMO
The presence of bone-marrow-derived stem cells was investigated in a wound-healing model where subcutaneously implanted cellulose sponges were used to induce granulation tissue formation. When cellulose was coated with hydroxyapatite (HA), the sponges attracted circulating haemopoietic and mesenchymal progenitor cells more efficiently than uncoated cellulose. We hypothesized that the giant cells/macrophages of HA-coated sponges recognize HA as foreign material, phagocyte or hydrolyse it and release calcium ions, which are recognized by the calcium-sensing receptors (CaRs) expressed on many cells including haemopoietic progenitors. Our results showed, indeed, that the HA-coated sponges contained more CaR-positive cells than untreated sponges. The stem cells are, most probably, responsible for the richly vascularized granulation tissue formed in HA-coated sponges. This cell-guiding property of HA-coated cellulose might be useful in clinical situations involving impaired wound repair.
Assuntos
Celulose/farmacologia , Implantes de Medicamento/farmacologia , Durapatita/farmacologia , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Tampões de Gaze Cirúrgicos , Cicatrização/efeitos dos fármacos , Animais , Células Cultivadas , Celulose/química , Implantes de Medicamento/química , Durapatita/química , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Granulation tissue was induced in hydroxyapatite-coated cellulose sponges with subcutaneous implantation in rats. A massive inflammatory reaction with an intense foreign body reaction and an increased invasion of fibrovascular tissue was observed by days 1-3 post-operation, whereas tissue growth into the uncoated control implants was much slower and took place mainly on their surfaces. The foreign body reaction in apatite-coated sponges declined after post-operative day 14, and no obvious differences were seen between the two cellulose sponges from 1 month up to 1 year after implantation. The apatite-coated implants attracted macrophages and fibroblasts, and favored angiogenesis. The excessive connective tissue formation was histologically normal, synthesized the major extracellular matrix molecules in a normal ratio and did not seem to disturb the animals in any way. These results warrant further investigations on clinical applicability of hydroxyapatite-coated cellulose sponges, when fast proliferation of connective tissue is desirable.
Assuntos
Celulose , Materiais Revestidos Biocompatíveis , Durapatita , Vidro , Tecido de Granulação/crescimento & desenvolvimento , Animais , Proteínas da Matriz Extracelular/genética , Tecido de Granulação/metabolismo , Implantes Experimentais , Macrófagos/citologia , Masculino , Teste de Materiais , Neovascularização Fisiológica , RNA/genética , RNA/metabolismo , Ratos , Ratos Sprague-Dawley , Tampões de Gaze Cirúrgicos , CicatrizaçãoRESUMO
Neurofibromatosis type 1 (NF1) is an inherited disease with an incidence of about 1:3000 worldwide. Approximately half of all patients with NF1 present osseous manifestations, which can vary from mild to severely debilitating changes such as congenital pseudarthrosis. In the present study, fracture healing of mouse tibia was followed and specimens were collected 5, 9, 14, and 22 days postoperatively. Experimental pseudarthrosis of rat was followed up to 15 weeks postoperatively. In situ hybridization and immunohistochemistry were used to demonstrate expression of NF1 tumor suppressor and phosphorylated p44/42 mitogen-activated protein kinase (MAPK), an indicator of the Ras-MAPK pathway. The results showed that ossified callus was formed in mouse fracture 22 days after the operation. The final outcome of rat pseudarthrosis was detected 9 weeks after the operation, presenting abundant cartilaginous callus at the pseudarthrosis. NF1 gene expression was noted in the maturing and in the hypertrophic cartilages during normal mouse fracture healing, and in rat pseudarthrosis. Phosphorylated p44/42 MAPK was detected in a subpopulation of the hypertrophic chondrocytes in both models. Furthermore, positive labeling for NF1 mRNA and protein was detected in endothelium in both the pseudarthrosis and in the fracture. In conclusion, NF1 gene expression and function are needed for normal fracture healing, possibly restraining excessive Ras-MAPK pathway activation.