Development of a computer-based quantification method for immunohistochemically-stained tissues and its application to study mast cells in equine wound healing (proof of concept).

BACKGROUND: There is a growing interest in the scientific community to use computer-based software programs for the quantification of cells during physiological and pathophysiological processes. Drawbacks of computer-based methods currently used to quantify immunohistochemical staining are the complexity of use, expense of software and overly-simplified descriptions of protocol thereby limiting reproducibility. The precise role of mast cells in equine cutaneous wound healing is unknown. Given the contribution of mast cells to the chronic inflammation observed in human keloid, a pathology similar to exuberant granulation tissue (EGT) in horses, mast cells might be present in high numbers in equine limb wounds predisposed to EGT. The main goal of this study was to develop a reliable and reproducible quantification method for immunostained tissues using a computer software that is widely available, at no cost, to the scientific community. A secondary goal was to conduct a proof of concept using the newly-established method to quantify mast cells during wound healing at different anatomical sites (body and limb) in horses to see if a different pattern is observed in limb wounds, which are predisposed to EGT. RESULTS: A good intraclass correlation coefficient (ICC, 0.67 p < 0.05) was found between the computer-based ImageJ method and manual counting. An excellent intra-operator ICC of 0.90 (p < 0.01) was found for the ImageJ quantification method while a good interoperator ICC of 0.69 (p < 0.01) was measured. No significant difference was observed between the variation of the ImageJ and that of the manual counting method. Mast cells were localized below the epidermis, around cutaneous appendages and blood vessels. Mast cell numbers did not differ significantly in relation to anatomical location or time of healing. CONCLUSIONS: The computer-based quantification method developed is reliable, reproducible, available, cost-free and could be used to study different physiological and pathological processes using immunohistochemistry.

Stem cell-like populations and immunoregulatory molecules in periodontal granulation tissue.

BACKGROUND AND OBJECTIVES: Determine the presence of mesenchymal stem cells (MSCs) in healthy periodontal tissue and periodontal granulation tissue (GT) and explore associations between immuno-regulatory molecules and selected subgingival microorganisms. MATERIAL AND METHODS: Mesenchymal stem cells were isolated, propagated and characterised by flow cytometry from a region of healthy gingival tissue and inflamed GT of 10 systemically healthy non-smokers with chronic periodontitis. Tissue levels of immunoregulatory molecules were determined by qPCR and Gingival Crevicular Fluid (GCF) levels by ELISA. Subgingival plaque levels of periodontal pathogens were determined by qPCR RESULTS: Cells with MSC-properties were isolated from both inflamed GT and healthy gingival (G) tissue. A pro-inflammatory process predominated in GT which was partly reflected in GCF and putative periodontal pathogens were higher at diseased sites. However, there was no significant difference in surface levels of mesenchymal (CD90, CD73, CD146, CD271, STRO-1), endothelial (CD105, CD106), hematopoietic (CD34, CD45) and embryonic (SSEA-4) stem cell markers between MSCs isolated from GT and G tissue. CONCLUSION: Periodontal lesions, albeit inflamed, retain healing potential as inferred by the presence of MSC-like cells with similar immunophenotypic characteristics to those found in healthy periodontal tissue. Therefore, there might be merits for healing in preserving sufficient GT in-situ during periodontal surgery.

Direct conversion of injury-site myeloid cells to fibroblast-like cells of granulation tissue.

Inflammation, following injury, induces cellular plasticity as an inherent component of physiological tissue repair. The dominant fate of wound macrophages is unclear and debated. Here we show that two-thirds of all granulation tissue fibroblasts, otherwise known to be of mesenchymal origin, are derived from myeloid cells which are likely to be wound macrophages. Conversion of myeloid to fibroblast-like cells is impaired in diabetic wounds. In cross-talk between keratinocytes and myeloid cells, miR-21 packaged in extracellular vesicles (EV) is required for cell conversion. EV from wound fluid of healing chronic wound patients is rich in miR-21 and causes cell conversion more effectively compared to that by fluid from non-healing patients. Impaired conversion in diabetic wound tissue is rescued by targeted nanoparticle-based delivery of miR-21 to macrophages. This work introduces a paradigm wherein myeloid cells are recognized as a major source of fibroblast-like cells in the granulation tissue.

Vascular endothelial growth factor receptor 1 (VEGFR1) tyrosine kinase signaling facilitates granulation tissue formation with recruitment of VEGFR1+ cells from bone marrow.

Vascular endothelial growth factor (VEGF)-A facilitates wound healing. VEGF-A binds to VEGF receptor 1 (VEGFR1) and VEGFR2 and induces wound healing through the receptor's tyrosine kinase (TK) domain. During blood flow recovery and lung regeneration, expression of VEGFR1 is elevated. However, the precise mechanism of wound healing, especially granulation formation on VEGFR1, is not well understood. We hypothesized that VEGFR1-TK signaling induces wound healing by promoting granulation tissue formation. A surgical sponge implantation model was made by implanting a sponge disk into dorsal subcutaneous tissue of mice. Granulation formation was estimated from the weight of the sponge and the granulation area from the immunohistochemical analysis of collagen I. The expression of fibroblast markers was estimated from the expression of transforming growth factor-beta (TGF-ß) and cellular fibroblast growth factor-2 (FGF-2) using real-time PCR (polymerase chain reaction) and from the immunohistochemical analysis of S100A4. VEGFR1 TK knockout (TK-/-) mice exhibited suppressed granulation tissue formation compared to that in wild-type (WT) mice. Expression of FGF-2, TGF-ß, and VEGF-A was significantly suppressed in VEGFR1 TK-/- mice, and the accumulation of VEGFR1+ cells in granulation tissue was reduced in VEGFR1 TK-/- mice compared to that in WT mice. The numbers of VEGFR1+ cells and S100A4+ cells derived from bone marrow (BM) were higher in WT mice transplanted with green fluorescent protein (GFP) transgenic WT BM than in VEGFR1 TK-/- mice transplanted with GFP transgenic VEGFR1 TK-/- BM. These results indicated that VEGFR1-TK signaling induced the accumulation of BM-derived VEGFR1+ cells expressing F4/80 and S100A4 and contributed to granulation formation around the surgically implanted sponge area in a mouse model.

Cultured Human Epidermis Combined With Meshed Skin Autografts Accelerates Epithelialization and Granulation Tissue Formation in a Rat Model.

INTRODUCTION: As the take rate of cultured epidermal autografts in burn wound treatment is variable, widely expanded meshed auto skin grafts are often used in combination with cultured epidermal autograft to increase the take rate and achieve definitive wound coverage. However, a long time (3-4 weeks) required to prepare a cultured epidermis sheet is a disadvantage. Allogeneic cultured epidermis can be prepared in advance and cryopreserved to be used in combination with auto meshed skin grafts for treating third-degree burns. Nevertheless, the human cultured epidermis (hCE) has not been proved to accelerate wound healing after meshed skin grafting. Here, we investigated the effect of hCE on wound healing in a rat model of meshed skin grafting. MATERIALS AND METHODS: Human cultured epidermis was prepared from human neonatal foreskin and assessed by the release of growth factors into the culture medium using enzyme-linked immunosorbent assay. Skin wounds were inflicted on male F344 rats and treated by the application of widely meshed (6:1 ratio) autogenous skin grafts with or without hCE (n = 8 rats per group). Wound area, neoepithelium length, granulation tissue formation, and neovascularization were evaluated on day 7 postgrafting. RESULTS: Human cultured epidermis secreted IL-1α, Basic fibroblast growth factor, platelet-derived growth factor-AA, TGF-α, TGF-ß1, and vascular endothelial growth factor in vitro. In rats, hCE accelerated wound closure (P = 0.003), neoepithelium growth (P = 0.019), and granulation tissue formation (P = 0.043), and increased the number of capillaries (P = 0.0003) and gross neovascularization area (P = 0.008) compared with the control group. CONCLUSIONS: The application of hCE with meshed grafts promoted wound closure, possibly via secretion of growth factors critical for cell proliferation and migration, suggesting that hCE can enhance the healing effect of widely expanded skin autografts.

Efeitos do PDGF-BB na taxa de proliferação e na adesão de células derivadas da granulação óssea a fragmentos radiculares / Effects of PDGF-BB on the rate of proliferation and on the adhesion of human cells derived from bone granulation tissue to root fragments

O objetivo deste estudo foi investigar o papel do fator de crescimento derivado de plaquetas-BB (PDGF-BB) na concentração de 300ng/ml na taxa de proliferação e adesão de células derivadas da granulação óssea humana a fragmentos radiculares periodontalmente comprometidos. Na primeira etapa do estudo, foi estabelecida cultura primária de células da granulação óssea de dois pacientes adultos, sistemicamente saudáveis, não fumantes. Após a expansão celular, as células foram caracterizadas para determinação do fenótipo por meio de ensaios de viabilidade celular, MTT, ensaio de atividade de fosfatase alcalina, ensaio de mineralização e caracterização imunohistoquímica por meio de citometria de fluxo (segunda etapa). Na terceira etapa do estudo, os efeitos da adição de PDGF-BB recombinante humano na concentração de 300ng/ml na taxa de proliferação e adesão de células derivadas da granulação óssea a superfícies radiculares periodontalmente comprometidas foram investigados. A taxa de proliferação celular estimulada pelo PDGF-BB (grupo teste) ou pelo meio de cultura (grupo controle) foi investigada por meio de contagem de células viáveis nos frascos de cultura após 1, 3, 5 e 7 dias do cultivo celular. Foram obtidos 30 fragmentos dentários a partir de dentes extraídos por razões periodontais. Os fragmentos foram raspados com curetas Gracey e condicionados com solução em gel de EDTA a 24% durante 3 minutos, lavados com solução de soro fisiológico, secos e posicionados em placas de 24 poços. Foram incubadas sobre os fragmentos tratados 1x104 células GO por 24 horas, seguido por fixação e preparo para análise por microscopia eletrônica de varredura (MEV). O número de células aderidas sobre os fragmentos foi analisado nas fotomicrografias. O padrão de crescimento das células GO foi compatível com células ósseas, com modificação do padrão do crescimento com o aumento do número de passagens. Houve atividade de fosfatase alcalina em meio osteogênico e convencional, com pico máximo aos 7 dias e atividade de mineralização estimulada ou não por meio osteogênico, com pico máximo aos 21 dias. A análise por meio de citometria de fluxo demonstrou que as células GO não expressaram CD105 e CD166 na 14a passagem, indicando sua diferenciação celular avançada nesse período. A adição de rhPDGF-BB resultou em mudança na taxa de proliferação celular, observando-se pico máximo de crescimento aos 7 dias, com diferenças estatisticamente significantes (p < 0.005; ANOVA post hoc Tukey) em relação aos períodos de 1, 3 e 5 dias. O ensaio de MTT demonstrou maior viabilidade celular no período de 48 hs, comparativamente aos períodos de 24 e 72 horas, quando a densidade óptica celular diminuiu de forma significativa (p< 0.05; Friedmann pósteste Dunn). No ensaio de adesão celular, pode-se observar que a adição de rhPDGFBB aumentou significativamente o número de células aderidas aos fragmentos dentários (p< 0.05; teste t não pareado com correção Welch), com alteração da morfologia celular. Esses resultados sugerem que as células GO tem características compatíveis com linhagem de células osteoblásticas, de fenótipo mais diferenciado após a 12a passagem. A adição de rhPDGF-BB (300ng/ml) resulta em aumento da taxa de proliferação das células GO e do número de células aderidas a fragmentos radiculares, indicando que, nesta concentração, o fator de crescimento é citocompatível, favorecendo a proliferação e adesão celular.(AU)

The goal of this study was to investigate the effects of recombinant human platelet derived growth factor (rhPDGF-BB) at the concentration of 300ng/ml in the proliferation and adhesion of human bone granulation cells to periodontally diseased root fragments. At the first stage of the study, the granulation tissue existent in healing sockets (21 days after its creation) was collected from two systemically healthy nonsmoking adults to the establishment of primary culture. The in vitro properties of bone granulation (BG) cell lineage were characterized by cell viability, MTT, alkaline phosphatase activity and mineralization assays. The effects of culture medium (control) and rhPGDF-BB 300ng/ml (test) in the proliferation and adhesion of BG cells were investigated. The rate of BG cells proliferation was investigated by the number of viable cells present at 1, 3, 5 and 7 days after platting. Thirty root fragments were obtained from teeth extracted for periodontal reasons. Root fragments were scaled and root planed, conditioned with EDTA 24% for 3 minutes, rinsed in saline solution, air-dryed and positioned in 24-well plates. Each fragment was seeded with 104 BG cells, fixated after 24 hours and prepared for analysis in SEM. The number of cells adhered to the fragments was analysed in photomicrographies. BG cells growth pattern was compatible with osteogenic cell lineage, showing modification with the increasing number of cell passage. GO cells expressed alkaline phosphatase activity in conventional and osteogenic culture medium, with maximum peak at 7 days, as well as mineralization activity stimulated or not by osteogenic or non-osteogenic culture medium, with maximum peak at 21 days. The analysis by flow cytometer showed that BG cells have not expressed CD105 and CD106 at the 14th passage, indicating its advanced cell differentiation. The addition of rhPDGF-BB resulted in modification of proliferation rate, with maximum peak observed at 7 days, significantly different from 1-, 3- and 5-day periods (p< 0.005; ANOVA post hoc Tukey). MTT assay showed greater cell viability after 48 hours than after 24 and 72 hours, when optical density has significantly diminished (p< 0.05; Friedmann post hoc Dunn). At cell adhesion assay, it could be observed that the adhesion of rhPDGF-BB has significantly increased the number of cells adhered to root fragments (p< 0.05; unpaired t test with Welchs correction), and alterations in cell morphology. These results suggest that BG cells present in vitro characteristics compatible with osteoblastic cell lineages, with a more differentiated phenotype after the 12th passage. The addition of rhPDGF-BB (300 ng/ml) results in increase of the rate of BG cell proliferation and in the number of cells adhered to root fragments, indicating that, at this concentration, the growth factor is compatible with BG cells and favors cells proliferation and adhesion.(AU)

Reactive Soft Tissue Preservation in Maxillary Large Bone Defects.

PURPOSE: Granulation tissue containing reactive soft tissue with potential multipotent stem cells can help socket healing following extraction. The aim of this study was to assess bone healing of maxillary large bone defects while maintaining reactive soft tissue. MATERIALS AND METHODS: A total of 32 patients presenting large bone defects were selected for this prospective study. Eight patients (Group A) presented with large bone defects but an intact buccal cortical plate, while 24 patients (Group B) presented with large bone defects lacking a buccal cortical plate. Teeth were extracted, and reactive soft tissue was left in the defects. Bone volume was assessed through cone beam computed tomography (CBCT) both before tooth extraction and at 4 months. A histomorphometric evaluation was performed. RESULTS: CBCT and cylinder bone cores were obtained for histology and histomorphometry analysis. At 4 months after tooth extraction, CBCT showed bone volume preservation and bone formation and no statistically significant difference in bone volume before and after tooth extraction in group A. However, in group B, over the same time period, a statistically significant increase (P < .01) of vertical bone volume was reported. Biopsy specimens showed the presence of vital bone in the defects 4 months later. CONCLUSION: Reactive soft tissue left in large bone defects after tooth extraction may support a significant bone volume gain and vital bone formation.

Effect of autologous platelet-rich plasma application on cutaneous wound healing in dogs.

This study was conducted to identify the effectiveness of platelet-rich plasma (PRP) and efficacy of intralesional injection as a method of application to acute cutaneous wounds in dogs. Healthy adult beagles (n = 3) were used in this study. Autologous PRP was separated from anticoagulant treated whole blood in three dogs. Cutaneous wounds were created and then treated by intralesional injection of PRP in the experimental group, while they were treated with saline in the control group on days 0, 2 and 4. The healing process was evaluated by gross examination throughout the experimental period and histologic examination on day 7, 14 and 21. In PRP treated wounds, the mean diameter was smaller and the wound closure rate was higher than in the control. Histological study revealed that PRP treated wounds showed more granulation formation and angiogenesis on day 7, and faster epithelialization, more granulation formation and collagen deposition were observed on day 14 than in control wounds. On day 21, collagen deposition and epithelialization were enhanced in PRP treated groups. Overall, PRP application showed beneficial effects in wound healing, and intralesional injection was useful for application of PRP and could be a good therapeutic option for wound management in dogs.

Radioresistance of granulation tissue-derived cells from skin wounds combined with total body irradiation.

Combined radiation and wound injury (CRWI) occurs following nuclear explosions and accidents, radiological or nuclear terrorism, and radiation therapy combined with surgery. CRWI is complicated and more difficult to heal than single injuries. Stem cell­based therapy is a promising treatment strategy for CRWI, however, sourcing stem cells remains a challenge. In the present study, the granulation tissue-derived cells (GTCs) from the skin wounds (SWs) of CRWI mice (C­GTCs) demonstrated a higher radioresistance to the damage caused by combined injury, and were easier to isolate and harvest when compared with bone marrow­derived mesenchymal stromal cells (BMSCs). Furthermore, the C-GTCs exhibited similar stem cell-associated properties, such as self-renewal and multilineage differentiation capacity, when compared with neonatal dermal stromal cells (DSCs) and GTCs from unirradiated SWs. Granulation tissue, which is easy to access, may present as an optimal autologous source of stem/progenitor cells for therapeutic applications in CRWI.

Efeitos dos tratamentos mecânico, químico e fotodinâmico na proliferação de células da granulação óssea humana sobre raízes dentárias / The effects of mechanical, chemical and photodynamic treatment on the proliferation of osseous granulation cells on dental roots

A técnica do enxerto de granulação óssea tem demonstrado bons resultados na recuperação do periodonto e na melhora dos parâmetros clínicos dos dentes com comprometimento periodontal. Pouco se sabe porém, a respeito de qual tipo de tratamento de superfície radicular se faz mais condizente com o emprego dessa técnica. O objetivo dessa pesquisa foi avaliar a proliferação de células de granulação óssea sobre fragmentos radiculares com os seguintes tratamentos de superfície: Controle - somente raspagem, EDTA, terapia fotodinâmica (PDT- laser InGaAIP - 30mW, 30s, 45J/cm², 660nm + azul de toluidina), e ácido cítrico com tetraciclina. Todos os grupos teste receberam previamente tratamento com raspagem e alisamento com 20 golpes de cureta. Células de granulação óssea foram cultivadas em quadruplicata sobre os fragmentos por um período de 24, 48 e 72 horas. Após esse período de cultivo os fragmentos foram fixados para análise em microscópio eletrônico de varredura (MEV). Cinco campos por fragmento foram usados para a visualização e contagem de células aderidas a superfície radicular (centro, campo superior direito e esquerdo e campo inferior direito e esquerdo). A análise da calibração do examinador foi feita através de uma combinação de testes estatísticos como erro casual de Dahlberg, erro sistemático e correlação de Pearson (p<0,05). A análise da amostra foi realizada através do ANOVA de medidas repetidas complementado por Tukey, com nível de significância de 5% (p<0,05). Os resultados demostraram diferenças estatisticamente significantes, quanto ao numero de células, para as superfícies tratadas com terapia fotodinâmica no período de 72 h (p<0,05). Através de nossos resultados concluímos que o tratamento radicular com terapia fotodinâmica favorece a proliferação de células de granulação óssea humanas in vitro.(AU)

The osseous granulation graft has been demonstrating good results on the periodontal healing, resulting the improvement of clinical periodontal parameters. There are very few knowledge about what kind of dental surface would be more proper for the application of this technique. The aim of this study was to evaluate the proliferation of osseous granulation cells on human root fragments treated by different techniques as scaling and root planning (control), citric acid plus tetracycline, EDTA and photodynamic therapy (PDT InGaAIP, 45J/cm², 30mW, 30s, 660nm, toluidine blue O). All test groups were previously treated which 20 curette strikes. Osseous granulation cells was culture in quadruplicate on these fragments for 24h, 48h and 72h. After that, all fragments were fixed and prepared for analysis in Scanning Electron Microscopy (SEM). Aiming to counting the cells adhered on the roots, we obtained electron micrographs of 5 areas (center, upper right and left field, lower right and left field). The examiner calibration was analyzed by Dahlberg Casual Error measurement, systematic error test and Pearson correlation test (p<0.05). Statistical analysis was performed by ANOVA, followed by Tukey test, with a 5% level of significance (p<0.05). There were significant differences in cell number after 72h culture in favor of PDT group (p<0,05). We can conclude that the surface treatment of roots which PDT favor the proliferation of osseous granulation cells in vitro.(AU)

Effect of autologous platelet-rich plasma application on cutaneous wound healing in dogs

This study was conducted to identify the effectiveness of platelet-rich plasma (PRP) and efficacy of intralesional injection as a method of application to acute cutaneous wounds in dogs. Healthy adult beagles (n = 3) were used in this study. Autologous PRP was separated from anticoagulant treated whole blood in three dogs. Cutaneous wounds were created and then treated by intralesional injection of PRP in the experimental group, while they were treated with saline in the control group on days 0, 2 and 4. The healing process was evaluated by gross examination throughout the experimental period and histologic examination on day 7, 14 and 21. In PRP treated wounds, the mean diameter was smaller and the wound closure rate was higher than in the control. Histological study revealed that PRP treated wounds showed more granulation formation and angiogenesis on day 7, and faster epithelialization, more granulation formation and collagen deposition were observed on day 14 than in control wounds. On day 21, collagen deposition and epithelialization were enhanced in PRP treated groups. Overall, PRP application showed beneficial effects in wound healing, and intralesional injection was useful for application of PRP and could be a good therapeutic option for wound management in dogs.

Induction of granulation tissue for the secretion of growth factors and the promotion of bone defect repair.

BACKGROUND: The use of the Masquelet technique in the repair of large bone defects has gained increased acceptance in recent years. The core of this technique is the induction of granulation tissue membrane formation and the implantation of an autologous cancellous bone to reconstruct bone defects in the membrane. In this study, we purpose to explore the structure of induced membrane and the content of growth factors as well to compare between the structure and the effects on osteogenesis of induced membranes and the periosteum in animal models. METHODS: Bilateral radial bone defects were generated in 32 healthy adult rabbits. The defects were implanted with bone cement. The induced membranes and periosteum were removed after 2, 4, 6, and 8 weeks. Thereafter, hematoxylin-eosin staining (HE) and an enzyme-linked immunosorbent assay (ELISA) were performed to detect vascular endothelial growth factor (VEGF), angiotensin II (ANG-II), bone morphogenetic protein 2 (BMP2), fibroblast growth factor 2 (FGF2), and prostaglandin E2 (PGE2). Proteins isolated from total cell lysates were cultured with mesenchymal stem cells to test the cell proliferation and alkaline phosphatase activity using epimysium as a control. RESULTS: The induced membrane and periosteum exhibited similar structures and growth factor levels after 4 and 6 weeks. The highest concentration of BMP-2 and VEGF in the induced membranes occurred in week 6, and FGF-2 and ANG-II concentrations peaked in week 4. The thickness and vascular density of induced membranes gradually decreased with time. CONCLUSION: Induced membrane matured between the 4th and the 6th week and secreted growth factors to promote osteogenesis. The matured induced membrane and periosteum had similar structures and abilities to promote the osteogenesis of mesenchymal stem cells. However, the induced membrane was thicker than the periosteum.

Activation and regulation of the granulation tissue derived cells with stemness-related properties.

INTRODUCTION: Skin as the largest and easily accessible organ of the body represents an abundant source of adult stem cells. Among them, dermal stem cells hold great promise in tissue repair and the skin granulation tissue has been recently proposed as a promising source of dermal stem cells, but their biological characteristics have not been well investigated. METHODS: The 5-bromo-2'-deoxyuridine (BrdU) lineage tracing approach was employed to chase dermal stem cells in vivo. Granulation tissue derived cells (GTCs) were isolated and their in vitro proliferation, self-renewing, migration, and multi-differentiation capabilities were assessed. Combined radiation and skin wound model was used to investigate the therapeutic effects of GTCs. MicroRNA-21 (miR-21) antagomir was used to antagonize miR-21 expression. Reactive oxygen species (ROS) were scavenged by N-acetyl cysteine (NAC). RESULTS: The quiescent dermal stem/progenitor cells were activated to proliferate upon injury and enriched in granulation tissues. GTCs exhibited enhanced proliferation, colony formation and multi-differentiation capacities. Topical transplantation of GTCs into the combined radiation and skin wound mice accelerated wound healing and reduced tissue fibrosis. Blockade of the miR-21 expression in GTCs inhibited cell migration and differentiation, but promoted cell proliferation and self-renewing at least partially via a ROS dependent pathway. CONCLUSIONS: The granulation tissue may represent an alternative adult stem cell source in tissue replacement therapy and miR-21 mediated ROS generation negatively regulates the stemness-related properties of granulation tissue derived cells.

Mesenchymal stem/progenitor cell isolation from tooth extraction sockets.

Bone marrow-derived mesenchymal stem/progenitor cells (BMSCs) are commonly used in regeneration therapy. The current primary source of BMSCs is the iliac crest; however, the procedure is associated with various burdens on the patient, including the risk of pain and infection. Hence, the possibility to collect BMSCs from other, more accessible, sources would be an attractive approach. It is well known that stem cells migrate from surrounding tissues and play important roles in wound healing. We thus hypothesized that stem/progenitor cells could be isolated from granulation tissue in the dental socket, and we subsequently collected granulation tissue from dog dental socket 3 d after tooth extraction. After enzyme digestion of the collected tissue, the cells forming colonies constituted the dental socket-derived stem/progenitor cells (dDSCs). Next, dDSCs were compared with dog BMSCs (dBMSCs) for phenotype characterization. A flow cytometric analysis showed that dDSCs were positive for CD44, CD90, and CD271 but negative for CD34 and CD45, similar to dBMSCs. dDSCs also exhibited osteogenic, adipogenic, and chondrogenic differentiation ability, similar to dBMSCs, with a higher capacity for colony formation, proliferation, and motility than dBMSCs. In addition, an in vivo ectopic bone formation assay showed that dDSCs and dBMSCs both induced hard tissue formation, although only dDSCs formed a fibrous tissue-like structure connected to the newly formed bone. Finally, we tested the ability of dDSCs to regenerate periodontal tissue in a one-wall defect model. The defects in the dDSC-transplanted group (ß-TCP/PGA/dDSCs) were regenerated with cementum-like and periodontal ligament-like tissues and alveolar bone, whereas only bony tissue was observed in the control group (ß-TCP/PGA). In conclusion, we identified and characterized a population of stem/progenitor cells in granulation tissue obtained from the dental socket that exhibited several characteristics similar to those of BMSCs. Dental sockets could therefore be a novel source for isolating stem/progenitor cells from bone.

The thymus and skin wound healing in Xenopus laevis adults.

The capacity to heal wounds without scars is generally lost during the development in vertebrates. To explore the involvement of cells of the adaptive immune system in a scar-like tissue based repair, we studied the thymus in 15-month-old Xenopus after skin incisional wounding. After injury, the organ size significantly increased and marked changes in structure and TNF-α immunoreactivity were detected in the medullary microenvironment when the granulation tissue was present in the repair area. Most of the lymphocytes present in this wound connective tissue were found to be immunoreactive to specific T cell markers. Thymic mucocyte-like cells and epithelial cysts increased in number, the myoid cells acquired a faster turnover and associated in large clusters, blood vessels were dilated and corpuscles similar to mammalian Hassall's bodies were formed in medulla. A higher number of stronger medullary TNF-α immunoreactive cells, i.e., dendritic, epithelial, granular basophilic and myoid cells were also induced after wounding. With progression of healing the thymus gradually returned to histochemical patterns of controls. Our results suggest that during the scar-based skin repair of Xenopus adults the activity of the thymus may be stimulated and associated with the T lymphocyte infiltration observed into injured granulation tissue.

MicroRNAs as regulators of cutaneous wound healing.

MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of gene expression, and have displayed important roles in areas spanning from embryonic development to skin physiology. Despite this, till now little is known about the significance of miRNAs in cutaneous wound healing. In this mini-review, we discuss the existing evidence on the roles of miRNAs in physiological processes relevant to cutaneous wound healing, followed by a highlight of the prospects and challenges of future development of miRNA-based wound therapies. With existing technologies of nucleic acid transfer and miRNA modulation, it is anticipated that once the roles of miRNAs in wound healing have been clarified, there will be a vast new vista of opportunities brought up for development of miRNA-targeted therapies for wound care.

A novel small compound accelerates dermal wound healing by modifying infiltration, proliferation and migration of distinct cellular components in mice.

BACKGROUND: Impaired wound healing in skin ulcer is one of the major medical issues in the aged society. Wound healing is a complex process orchestrated by a number of humoral factors and cellular components. TGF-ß is known to stimulate collagen production in dermal fibroblasts while inhibiting proliferation of epidermal keratinocyte. A screening of small compounds that suppress type I collagen production in fibroblasts has identified HSc025 that antagonizes the TGF-ß/Smad signal. OBJECTIVE: We examined the effects of HSc025 on dermal wound healing and elucidated the underlying mechanisms. METHODS: Effects of HSc025 on the wound closure process were evaluated in a murine full-thickness excisional wound healing model. Cell proliferation and migration were estimated using primary cultures of human keratinocytes and fibroblasts. Comprehensive analyses of gene expression profiles were performed using untreated and HSc025-treated fibroblasts. RESULTS: Oral HSc025 administration suppressed macrophage infiltration and accelerated wound closure as early as at day 2 after the dermal excision. Treatment of cultured keratinocytes with HSc025 counteracted the inhibitory effects of TGF-ß on cell proliferation and migration. On the other hand, HSc025 stimulated migration, but not proliferation, of dermal fibroblasts independently of TGF-ß. Experiments using an artificial dermis graft revealed that HSc025 stimulated migration of collagen-producing cells into the graft tissue. A cDNA microarray analysis of untreated and HSc025-treated fibroblasts identified pirin as a critical mediator accelerating fibroblast migration. CONCLUSION: HSc025 accelerates wound healing by modifying infiltration, proliferation and migration of distinct cellular components, which provides a novel insight into the therapy for intractable skin ulcer.

Numerical simulation of electrically stimulated osteogenesis in dental implants.

Cell behavior and tissue formation are influenced by a static electric field (EF). Several protocols for EF exposure are aimed at increasing the rate of tissue recovery and reducing the healing times in wounds. However, the underlying mechanisms of the EF action on cells and tissues are still a matter of research. In this work we introduce a mathematical model for electrically stimulated osteogenesis at the bone-dental implant interface. The model describes the influence of the EF in the most critical biological processes leading to bone formation at the bone-dental implant interface. The numerical solution is able to reproduce the distribution of spatial-temporal patterns describing the influence of EF during blood clotting, osteogenic cell migration, granulation tissue formation, displacements of the fibrillar matrix, and formation of new bone. In addition, the model describes the EF-mediated cell behavior and tissue formation which lead to an increased osteogenesis in both smooth and rough implant surfaces. Since numerical results compare favorably with experimental evidence, the model can be used to predict the outcome of using electrostimulation in other types of wounds and tissues.

[A method for the primary culture of fibroblasts isolated from human airway granulation tissues].

OBJECTIVE: To establish a feasible method to culture primary fibroblasts isolated from human airway granulation tissues, and therefore to provide experimental data for the investigation of the pathogenesis of benign airway stenosis. METHODS: The granulation tissues were collected from 6 patients during routine bronchoscopy at our department of Beijing Tiantan Hospital from April to June 2011. Primary fibroblasts were obtained by culturing the explanted tissues. Cell growth was observed under inverted microscope. RESULTS: All of these 6 primary cultures were successful. Fibroblast-like cells were observed to migrate from the tissue pieces 3 d after inoculation. After 9-11 d of culture, cells reached to 90% confluence and could be sub-cultured. After passage, the cells were still in a typical elongated spindle-shape and grew well. The cells could be sub-cultured further when they formed a monolayer. CONCLUSION: Explant culture is a reliable method for culturing primary fibroblasts from human airway granulation tissues.

[Case of inflammatory lesion in urinary bladder showing high signal intensity on diffusion-weighted MRI: correlation with histopathological finding].

A 66-year-old woman was referred to our department for thickening bladder wall incidentally found during postoperative follow-up of transverse colon cancer. Cystoscopy showed edematous tumor with a diameter of 5 cm on the right wall. Deep portion of the tumor showed high intensity on diffusion-weighted magnetic resonance imaging (DW-MRI). Transurethral resection and transvaginal needle biopsy was performed, and pathological examination revealed granulation tissues mainly consisted of inflammatory cells and fibrosis. DW-MRI is a functional imaging constructed by quantifying the diffusion of water molecules. Recently, the feasibility of this imaging in the diagnosis of bladder cancer has been reported. However, we should keep in mind that granulation tissues consisted of inflammatory cells and fibrosis is also possible to be positive for DW-MRI.