Dose-dependent impairment of collagen deposition by topical granulocyte-macrophage colony-stimulating factor in human experimental wounds

Immune evaluation of granulocyte-macrophage colony stimulating factor loaded hierarchically 3D nanofiber scaffolds in a humanized mice model

Background: Immune evaluation of biomaterials for tissue regeneration is a critical preclinical evaluation. The current evaluation criterion (ISO 10993-1 or GB/T 16886) uses rodents to perform the immune evaluation. However, the immune system of rodents is different from humans, the obtained results may not be reliable, which could lead directly to the failure of clinical trials. Granulocyte-macrophage colony-stimulating factor (GM-CSF) shows a great potential application in tissue regeneration by regulating local immune responses. The presented work combines the advantages of GM-CSF (immunoregulation) and hierarchically 3D nanofiber scaffolds (tissue regeneration). Methods: Firstly, we fabricated GM-CSF loaded 3D radially aligned nanofiber scaffolds, and then subcutaneous implantation was performed in humanized mice. The whole scaffold and surrounding tissue were harvested at each indicated time point. Finally, the cell infiltration and local immune responses were detected by histological observations, including H&E and Masson staining and immunochemistry. Results: We found significant cell migration and extracellular matrix deposition within the 3D radially aligned nanofiber scaffold after subcutaneous implantation. The locally released GM-CSF could accelerate the expression of human dendritic cells (CD11c) only 3 days after subcutaneous implantation. Moreover, higher expression of human cytotoxic T cells (CD3⁺/CD8⁺), M1 macrophages (CD68/CCR7) was detected within GM-CSF loaded radially aligned nanofiber scaffolds and their surrounding tissues. Conclusions: The 3D radially aligned scaffold can accelerate cell migration from surrounding tissues to regenerate the wound area. And the locally released GM-CSF enhances dendritic cell recruitment and activation of cytotoxic T cells and M1 macrophages. Taken together, the GM-CSF loaded 3D radially aligned nanofiber scaffolds have a promising potential for achieving tissue regeneration.

Clinical application of growth factors and cytokines in wound healing

Wound healing is a complex and dynamic biological process that involves the coordinated efforts of multiple cell types and is executed and regulated by numerous growth factors and cytokines. There has been a drive in the past two decades to study the therapeutic effects of various growth factors in the clinical management of nonhealing wounds (e.g., pressure ulcers, chronic venous ulcers, diabetic foot ulcers). For this review, we conducted an online search of Medline/PubMed and critically analyzed the literature regarding the role of growth factors and cytokines in the management of these wounds. We focused on currently approved therapies, emerging therapies, and future research possibilities. In this review, we discuss four growth factors and cytokines currently being used on and off label for the healing of wounds. These include granulocyte-macrophage colony-stimulating factor, platelet-derived growth factor, vascular endothelial growth factor, and basic fibroblast growth factor. While the clinical results of using growth factors and cytokines are encouraging, many studies involved a small sample size and are disparate in measured endpoints. Therefore, further research is required to provide definitive evidence of efficacy.

Combined application of alginate dressing and human granulocyte-macrophage colony stimulating factor promotes healing in refractory chronic skin ulcers

The aim of the present study was to evaluate the clinical therapeutic effect of the combined application of alginate and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on the healing of refractory chronic skin ulcers. A single center, three arm, randomized study was performed at Jinan Central Hospital (Jinan, Shandong, China). A total of 60 patients with refractory chronic skin ulcers, which persisted for >1 month, were enrolled and randomly assigned into one of the following three groups: alginate dressing/rhGM-CSF group (group A), rhGM-CSF only group (group B) and conventional (vaseline dressing) group (group C). The wound area rate was measured, granulation and color were observed and pain was evaluated. The data were summarized and statistical analysis was performed. The results demonstrated that group A exhibited a significantly faster wound healing rate and lower pain score compared with the other groups (P<0.01). In conclusion, the combined application of alginate dressing and rhGM-CSF for the treatment of refractory chronic skin ulcers demonstrated significant advantages. It promoted the growth of granulation tissue, accelerated re-epithelialization and also effectively reduced wound pain, and thus improved the quality of life for the patient. This suggests that the combined application of alginate and rhGM-CSF may be an effective therapeutic strategy for the clinical treatment of refractory chronic skin ulcers.

Regulation of wound healing by granulocyte-macrophage colony-stimulating factor after vocal fold injury

Objectives

Vocal fold (VF) scarring remains a therapeutic challenge. Granulocyte-macrophage colony-stimulating factor (GM-CSF) facilitates epithelial wound healing, and recently, growth factor therapy has been applied to promote tissue repair. This study was undertaken to investigate the effect of GM-CSF on VF wound healing in vivo and in vitro.

Methods

VF scarring was induced in New Zealand white rabbits by direct injury. Immediately thereafter, either GM-CSF or PBS was injected into the VFs of rabbits. Endoscopic, histopathological, immunohistochemical, and biomechanical evaluations of VFs were performed at 3 months post-injury. Human vocal fold fibroblasts (hVFFs) were cultured with GM-CSF. Production of type I and III collagen was examined immunocytochemically, and the synthesis of elastin and hyaluronic acids was evaluated by ELISA. The mRNA levels of genes related to ECM components and ECM production-related growth factors, such as HGF and TGF-ß1, were examined by real time RT-PCR.

Results

The GM-CSF-treated VFs showed reduced collagen deposition in comparison to the PBS-injected controls (P<0.05). Immunohistochemical staining revealed lower amounts of type I collagen and fibronectin in the GM-CSF-treated VFs (P<0.05 and P<0.01, respectively). Viscous and elastic shear moduli of VF samples were significantly lower in the GM-CSF group than in the PBS-injected group (P<0.001 and P<0.01, respectively). Mucosal waves in the GM-CSF group showed significant improvement when compared to the PBS group (P = 0.0446). GM-CSF inhibited TGF-β1-induced collagen synthesis by hVFFs (P<0.05) and the production of hyaluronic acids increased at 72 hours post-treatment (P<0.05). The expressions of HAS-2, tropoelastin, MMP-1, HGF, and c-Met mRNA were significantly increased by GM-CSF, although at different time points (P<0.05).

Conclusion

The present study shows that GM-CSF offers therapeutic potential for the remodeling of VF wounds and the promotion of VF regeneration.

Platelet-rich fibrin versus albumin in surgical wound repair: a randomized trial with paired design

OBJECTIVE

To study the effects of autologous platelet-rich fibrin (PRF) versus human albumin on incisional wound breaking strength and subcutaneous collagen deposition in patients undergoing laparoscopic cholecystectomy in a randomized trial.

SUMMARY BACKGROUND DATA

Platelet peptidic growth factors may stimulate collagen synthesis and tissue repair.

METHODS

One expanded polytetrafluoroethylene (ePTFE) tube was inserted subcutaneously from the edge of each of the two 10-mm trocar incisions in 51 patients. Treatment with PRF prepared from the patient's own blood or human albumin was randomized to respective wound site by concealed allocation. On postoperative day 10, breaking strength of the incisional wounds as well as the collagen concentration, type I procollagen mRNA, type III procollagen mRNA, matrix metalloproteinase-1 mRNA, and fibroblast density in the ePTFE tubes were determined. All analyses were assessor-blinded. The trial was registered in the Current Controlled Trials Registry (ISRCTN34481461).

RESULTS

Local PRF had no significant effect on incisional wound-breaking strength. In the ePTFE tubes, PRF treatment decreased collagen concentration by 24% (P=0.046) and type I procollagen mRNA level by 29% (P=0.003), but had no significant impact on type III procollagen mRNA, matrix metalloproteinase-1 mRNA or fibroblast infiltration. The profibrotic transforming growth factor-beta1 level increased (P<0.0001) 2-fold with PRF. Collagen concentration in albumin-treated ePTFE tubes correlated with breaking strength of the skin incisions (rs=0.48, P=0.03).

CONCLUSIONS

PRF did not improve wound strength significantly compared with albumin but suppressed subcutaneous collagen synthesis and deposition during early repair of surgical wounds in humans. Furthermore, deposition of reparative collagen in the subcutaneous ePTFE tube model partly predicted the breaking strength of an incisional skin wound.

Evaluation of cellular wound healing using flow cytometry and expanded polytetrafluroethylene implants

In wound healing studies that investigate therapeutic interventions, it is important to characterize cellular responses. In a randomized trial enrolling patients at risk for surgical infection, one goal is to phenotype cells within a polytetrafluoroethylene implant using flow cytometry and immunohistochemistry, together with standard hematoxylin- and eosin-based histology. Subcutaneous implants are removed 8-9 days postoperatively. To obtain single cells associated with the mechanism of wound healing, we initially used a mouse skin digestion protocol. We optimized this to increase the cell yield and isolate sufficient cells for flow cytometry. The modifications increased the total cells recovered per subject from an average of 5.3 x 10(4)-41 x 10(4) with an average viability of 80%. The immunoflourescent staining assay was verified for our samples, which have smaller cell sample numbers than tissue biopsies. Thirty-two samples were stained. Cells from the polytetrafluoroethylene tubes were isolated and stained positively with fluorescent-labeled antibodies to CD3, CD20, CD31, CD34, CD68, CD133, and VEGF receptor type 2. Flow cytometry data correlated with immunohistochemistry data especially with respect to CD68. This antigen was the most prevalent in both the cell analysis methods. Our findings demonstrate that flow cytometry can be used with polytetrafluoroethylene samples as an additional evaluation method to document and describe cellular wound healing responses.

Cytokine profiling and Stat3 phosphorylation in epithelial-mesenchymal interactions between keloid keratinocytes and fibroblasts

We previously reported an increase in signal transducer and activator of transcription 3 (Stat3) activation in keloid fibroblasts, which contributes to collagen production, cell proliferation, and migration. We further investigated the effect of epithelial-mesenchymal interaction on Stat3 in normal and keloid fibroblasts in noncoculture and coculture conditions. pY705 Stat3 was higher in keloid fibroblasts compared to normal fibroblasts in noncoculture. However, a more drastic decrease in pY705 Stat3 was observed in keloid fibroblasts compared to normal fibroblasts when cocultured with their respective keratinocytes over 5 days. To explore this paracrine effect, we examined the secretion of cytokines by cytokine arrays. Altered cytokine production was detected in keloid fibroblasts and keratinocytes, either in noncoculture or coculture conditions. IL-6, IL-8, monocyte chemoattractant protein-1, tissue inhibitor of metalloproteinases (TIMPs)-1, and TIMP-2 were major cytokines detected. Angiogenin, oncostatin M (OSM), vascular endothelial cell growth factor, IGF-binding protein-1, osteoprotegerin, and transforming growth factor-beta2 were present in keloid keratinocyte-fibroblast coculture, but absent in normal keratinocyte-fibroblast coculture. Only IL-6 and OSM stimulated strong pY705 Stat3 and cell proliferation in both normal and keloid fibroblasts. Other cytokines increased proliferation of keloid fibroblasts, but not normal fibroblasts, suggesting an altered state in keloid fibroblasts. Multiple cytokines likely contribute to keloid pathogenesis and a combinatorial neutralizing antibody/cytokine therapy may be effective in ameliorating keloid scars.

The effects of topical granulocyte-macrophage colony-stimulating factor on dural healing in rats after induced cerebrospinal fluid leakage

OBJECT

Dural defects must be repaired to protect the central nervous system from contamination. Although there are various experimental and commercial substances available for this purpose, the ultimate method of watertight dural closure has yet to be discovered. In this study, the authors investigate the effects of topically applied recombinant mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) on dural healing in a rat model of dural injury and cerebrospinal fluid leakage.

METHODS

In this experimental model, a dural defect at the level of the L1-2 vertebrae was created in 32 Wistar rats. Sixteen animals were treated with locally applied recombinant mouse GM-CSF postoperatively, and 16 animals received normal saline. The effects of GM-CSF on dural healing, cerebrospinal fluid leakage, and wound healing were assessed 2 and 4 weeks postoperatively. Dural healing was evaluated histologically.

RESULTS

Dural healing was increased in rats treated with GM-CSF compared with rats in the control group. This difference was statistically significant (p < 0.05).

CONCLUSIONS

Cerebrospinal fluid leakage may impede healing of dural defects. Topically applied GM-CSF seems to aid in dural healing.

Granulocyte-macrophage colony-stimulating factor is essential for normal wound healing

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a multipotent growth factor, which plays an important role during the process of wound healing. In clinical settings it has occasionally been employed in the treatment of cutaneous wounds of diverse etiologies. In a previous study, we have shown the positive influence of GM-CSF on full thickness excisional wounds in transgenic mice overexpressing GM-CSF in the basal layer of the epidermis. Direct GM-CSF action as well as indirect processes through the induction of secondary cytokines were proposed to contribute towards the beneficial effects. In this study, we analyzed the process of wound healing in transgenic mice overexpressing a GM-CSF antagonist in the epidermis. These mice not only exhibited a delayed scab rejection and reepithelialization but also neovascularization was reduced. The newly formed tissue was of poor quality as exhibited by the presence of extensive fibrosis. We suggest that the presence of GM-CSF in the repair process is of basic importance and its absence leads not only to delayed wound healing but it is also detrimental for the quality of the newly formed tissue.

Emerging new drugs for wound repair

Every year, millions of people experience burns, suffer from nonhealing wounds, or have acute wounds that become complicated by infection, dehiscence or problematic scarring. Effective wound treatment requires carefully considered interventions often requiring multiple clinic or hospital visits. The resulting costs of wound care are staggering, and more efficacious and cost-effective therapies are needed to decrease this burden. Unfortunately, the expenses and difficulties encountered in performing clinical trials have led to a relatively slow growth of new treatment options for the wound management. Research efforts attempting to examine wound pathophysiology have been hampered by the lack of an adequate chronic wound healing model, and the complexity of the wound healing cascade has limited attempts at pharmacological modification. As such, currently available wound healing therapies are only partially effective. Therefore, many new therapies are emerging that target various aspects of wound repair and the promise of new therapeutic interventions is on the immediate horizon.

The effect of preoperative radiotherapy on systemic collagen deposition and postoperative infective complications in rectal cancer patients

PURPOSE

Preoperative, high-dose radiotherapy for rectal cancer reduces local recurrence rates and improves overall survival. However, adverse effects in varying degrees include impaired wound healing and local infection. This study investigates the influence of preoperative, high-dose radiotherapy on subcutaneous accumulation of collagen in a primary rectal cancer group operated on with or without adjuvant radiotherapy.

METHODS

Forty-two eligible patients who underwent total mesorectal excision surgery with or without radiotherapy were included in the study. Polytetrafluoroethylene tubings were implanted in the arm ten days before surgery (three days before the start of radiotherapy). Implants were extracted the day before surgery. New implants were inserted before surgery and were extracted ten days after surgery. The hydroxyproline and proline contents of the implants were measured and the hydroxyproline/proline ratio was calculated as a measure for deposited collagen relative to protein. Blood loss, postoperative complications, and blood levels of hemoglobin, leukocytes, and albumin were recorded.

RESULTS

The two groups were similar in relation to Dukes stage, age, and body mass index. Infectious complications developed in 39 percent of patients after radiotherapy compared with 16 percent in the nonirradiated group. In the irradiated patients with infective complications we found a significant decrease in the hydroxyproline/proline ratio compared with that of irradiated patients without infections (P = 0.037). There was a significant decrease in the leukocyte count preoperatively and postoperatively in the irradiated group compared with surgery alone.

CONCLUSIONS

High-dose, short-term radiotherapy does not have a systemic effect on collagen accumulation, but a significant reduction is manifested in infected patients. Radiotherapy also impairs leukocyte production and increases the postoperative infective complication rate.

Keratinocyte and dermal vascular endothelial cell capacities remain unimpaired in the margin of chronic venous ulcer

The role of endogenously produced cytokines and growth factors in the impaired healing of chronic leg ulcers remains uncertain. The aim of this study was to determine the functional capacity of skin cells in ulcer bed tissue compared to those in the edge of ulcers and skin distal to ulcers. Biopsies from leg ulcers of ten randomly selected patients were examined immunohistochemically for cytokines and growth factors produced by keratinocytes (KC) and vascular endothelial cells (EC). The phenotype of leukocytes infiltrating venous ulcers and the expression of vascular adhesion molecules responsible for extravasation were also studied. The expression of cytokines and growth factors by KC was similar in areas adjacent and remote from an ulcer. In the dermis adjacent to an ulcer, the expression of IL-1alpha, IL-1beta, IL-1Ra, EGF and PDGFa by EC was higher than the levels of expression in EC from the distant dermis. The expression of IL-6, TNFalpha and GM-CSF was comparable to that in cells from intact dermis. For all these factors staining was cytoplasmic, suggesting production in these areas. Ulcer bed tissue contained few fibroblasts and blood capillaries showing a high staining intensity for CD62E and CD106 EC adhesion molecules but no FGF2 expression (P<0.05). The intensity of staining for scavenging CD15+ elastase+ granulocytes and CD35+ (C3bR) activated macrophages in the ulcer bed was comparable to that in the margin but higher than that in the distant dermis (P<0.05), whereas staining for CD68+, HLA DR+, TGFbeta+ and CD54+ dermal macrophages was similar in all areas. There was reduced staining for CD4+ and CD8+ cells in the ulcer bed (P<0.05). There were no CD1a+ Langerhans cells in the epidermis encroaching upon the granulation tissue and there was reduced CD1a staining in the adjacent epidermis (P<0.05). In conclusion, there is chronic accumulation of scavenging cells with lack of remodeling of the granulation tissue and, at the same time, preserved cytokine and growth factor secretory potential of KC and dermal EC in non-healing venous leg ulcers.

Effect of granulocyte-macrophage colony-stimulating factor inducer on left ventricular remodeling after acute myocardial infarction

OBJECTIVES

We sought to determine the influence of granulocyte-macrophage colony-stimulating factor (GM-CSF) induction on post-myocardial infarction (MI) remodeling, especially in relation to the inflammatory response and myocardial fibrosis.

BACKGROUND

Granulocyte-macrophage colony-stimulating factor modifies wound healing by promoting monocytopoiesis and infiltration of monocytes and macrophages into injured tissue; however, the effect of GM-CSF induction on the infarct healing process and myocardial fibrosis is unclear.

METHODS

A model of MI was produced in Wistar rats by ligation of the left coronary artery. The MI animals were randomized to receive GM-CSF inducer (romurtide 200 microg/kg/day for 7 consecutive days) (MI/Ro) or saline (MI/C).

RESULTS

Echocardiographic and hemodynamic studies on day 14 revealed increased left ventricular (LV) end-diastolic dimension, decreased fractional shortening, elevated LV end-diastolic pressure, and decreased LV maximum rate of isovolumic pressure development in MI/Ro compared with MI/C. Immunoblotting showed that expression of transforming growth factor (TGF)-beta1 in the infarcted site on day 3 after MI was decreased in MI/Ro compared with MI/C. In the infarcted site, TGF-beta1, collagen type I and type III messenger ribonucleic acid (mRNA) expression on day 3, and collagen content on day 7 were reduced in MI/Ro compared with MI/C, in association with marked infarct expansion. In MI/Ro, monocyte chemoattractant protein-1 mRNA level and the degree of infiltration of monocyte-derived macrophages (ED-1-positive)were greater in the infarcted site on day 7 than those in MI/C.

CONCLUSIONS

The GM-CSF induction by romurtide facilitated infarct expansion in association with the promotion of monocyte recruitment and inappropriate collagen synthesis in the infarcted region during the early phase of MI.

Effects of granulocyte macrophage colony stimulating factor on random flap healing and immune profile in rats with impaired wound healing by glucocorticoids

Wound healing involves inflammation, cell proliferation, matrix deposition, and tissue remodeling. Priming the tissue to be incised with proinflammatory cytokines offers a new approach to wound healing. This has been studied mostly in incisional wounds till now. This study was designed to investigate the role of granulocyte macrophage colony stimulating factor (GM-CSF) priming of planned incision lines in random flaps in rats with impaired wound healing due to glucocorticoid administration, and immune profiles of rats were also evaluated. GM-CSF priming of incision lines in immunosuppressed rats was shown to improve the wound healing parameters, hydroxyproline levels, breaking strength, flap survival, and immune profile, although all of the parameters were somewhat lower than those of control group. The findings of this study suggest that wound healing can be accelerated and thus morbidity lowered by making use of the immunomodulator effects of GM-CSF in cases where wound healing is impaired due to systemic disease or drug use and flap reconstruction is necessary.