Role of cytokines in healing chronic skin wounds

Genetic and Epidemiological Similarities, and Differences Between Postoperative Intraperitoneal Adhesion Development and Other Benign Fibro-proliferative Disorders

Intraperitoneal adhesions complicate over half of abdominal-pelvic surgeries with immediate, short, and long-term sequelae of major healthcare concern. The pathogenesis of adhesion development is similar to the pathogenesis of wound healing in all tissues, which if unchecked result in production of fibrotic conditions. Given the similarities, we explore the published literature to highlight the similarities in the pathogenesis of intra-abdominal adhesion development (IPAD) and other fibrotic diseases such as keloids, endometriosis, uterine fibroids, bronchopulmonary dysplasia, and pulmonary, intraperitoneal, and retroperitoneal fibrosis. Following a literature search using PubMed database for all relevant English language articles up to November 2020, we reviewed relevant articles addressing the genetic and epidemiological similarities and differences in the pathogenesis and pathobiology of fibrotic diseases. We found genetic and epidemiological similarities and differences between the pathobiology of postoperative IPAD and other diseases that involve altered fibroblast-derived cells. We also found several genes and single nucleotide polymorphisms that are up- or downregulated and whose products directly or indirectly increase the propensity for postoperative adhesion development and other fibrotic diseases. An understanding of the similarities in pathophysiology of adhesion development and other fibrotic diseases contributes to a greater understanding of IPAD and these disease processes. At a very fundamental level, blocking changes in the expression or function of genes necessary for the transformation of normal to altered fibroblasts may curtail adhesion formation and other fibrotic disease since this is a prerequisite for their development. Similarly, applying measures to induce apoptosis of altered fibroblast may do the same; however, apoptosis should be at a desired level to simultaneously ameliorate development of fibrotic diseases while allowing for normal healing. Scientists may use such information to develop pharmacologic interventions for those most at risk for developing these fibrotic conditions.

Low current electrical stimulation upregulates cytokine expression in the anal sphincter

AIM

Stem cells are an emerging treatment for regeneration of damaged anal sphincter tissues. Homing to the site of injury can be potentiated by stromal derived factor 1 (SDF-1) and monocyte chemotactic protein 3 (MCP-3) expression. The effects of electrical stimulation (ES) on upregulation of these cytokines were investigated.

METHODS

The anal sphincter complex of Sprague Dawley rats was stimulated with current of 0.25 mA, pulse duration of 40 pulses/s, pulse width of 100 μs, and frequency of 100 Hz for 1 or 4 h. Sham was created using the same needle which was inserted into the anal sphincter without electrical stimulation in different groups of animals. The rats were euthanized immediately or 24 h after stimulation. Cytokine analysis was performed using real-time polymerase chain reaction. Statistical analysis was performed.

RESULTS

Results are presented as a fold increase compared to sham that was normalized to 1. SDF-1 and MCP-3 immediately after 1 h were 2.5 ± 0.77 and 3.1± 0.93 vs. sham, respectively, showing significant increase. After 1-h stimulation and euthanasia 24 h after, SDF-1 and MCP-3 were 1.49 ± 0.16 and 1.51± 0.14 vs. sham, respectively, showing significant increase. Immediately and 24 h after 4-h stimulation, SDF-1 was 1.21 ± 0.16 and 0.54 ± 0.16 vs. sham, respectively, and was not significantly different. Immediately and 24 h after 4-h stimulation, MCP-3 was 1.29 ± 0.41 and 0.35 ±1.0 vs. sham, respectively, and was not significantly different. SDF-1 and MCP-3 after 1 h were significantly higher than after 4 h of stimulation at both time points.

CONCLUSION

Electrical stimulation for 1 h significantly upregulates SDF-1 and MCP-3 expression that persists for 24 h. Prolonged stimulation reduced chemokine expression, suggesting electrolysis of cells.

Chemokine upregulation in response to anal sphincter and pudendal nerve injury: potential signals for stem cell homing

PURPOSE

Stromal derived factor-1 (SDF-1) and monocyte chemotactic protein-3 (MCP-3) are signals forcing the migration of bone marrow-derived stem cells to ischemic tissue. This study investigates SDF-1 and MCP-3 expression following direct injury to the anal sphincter and pudendal nerve and to determine if these same mechanisms have any role.

METHODS

Chemokine expression was studied after anal sphincter injury in female rats after either a sphincterotomy (n = 15), pudendal nerve crush (PNC; n = 15), sham pudendal nerve crush (n = 15), or acted as unmanipulated controls (n = 5). Analysis was done at 1 h and 10 and 21 days after injury.

RESULTS

After injury, SDF-1 expression increased 40.2 ± 6.42 (P = 0.01) at 1 h and 28.2 ± 2.37 (P = 0.01) at 10 days, respectively, compared to controls. Likewise, MCP-3 expression increased 40.8 ± 8.17 (P = 0.02) at the same intervals compared to controls. After PNC, SDF-1 expression increased 46.4 ± 6.01 (P = 0.02) and 50.6 ± 10.11 (P = 0.01), and MCP-3 expression increased 46.3 ± 7.76 (P = 0.03) and 190.8 ± 22.15 (P = 0.01), respectively, at the same time intervals compared to controls. However, when PNC was compared to sham injured, a significant increase was seen in SDF-1 and MCP-3 at 10 days. At 21 days, PNC compared to sham injured was significantly low in expression for both SDF-1 and MCP-3 (P < 0.05).

CONCLUSIONS

Direct anal sphincter injury results in higher levels of SDF-1 and MCP-3 expression soon after injury, whereas denervation via pudendal nerve crush results in greater SDF-1 and MCP-3 expression 10 days after injury. Chemokine overexpression suggests the potential for cell-based therapeutic strategies.

The science of wound bed preparation

The concept of wound bed preparation (WBP) heralded a new era in terms of how we treat wounds. It emphasized the difference between acute and chronic wounds, and it cemented the idea that the processes involved in the healing of acute wounds do not apply completely to the healing of chronic wounds. The arbitrary division of the normal healing process into the phases of hemostasis, inflammation, proliferation, and maturation addresses the events in acute wound healing. We have realized that the impediments to healing in chronic wounds lead to a failure to progress through these phases and are independent factors that make the chronic wound a much more complex condition. A major advance in resolving or addressing the chronic wound has been the concept of WBP. WBP allows us to address the problems of wound healing individually the presence of necrotic tissue, hypoxia, high bacterial burden, corrupt matrix, and senescent cells within the wound bed. In WBP we can optimize our therapeutic agents to accelerate endogenous healing or to increase the effectiveness of advanced therapies.

The science of wound bed preparation

The concept of wound bed preparation (WBP) heralded a new era in terms of how we treat wounds. It emphasized the difference between acute and chronic wounds, and it cemented the idea that the processes involved in the healing of acute wounds do not apply completely to the healing of chronic wounds. The arbitrary division of the normal healing process into the phases of hemostasis, inflammation, proliferation, and maturation addresses the events in acute wound healing. We have realized that the impediments to healing in chronic wounds lead to a failure to progress through these phases and are independent factors that make the chronic wound a much more complex condition. A major advance in resolving or addressing the chronic wound has been the concept of WBP. WBP allows us to address the problems of wound healing individually-the presence of necrotic tissue, hypoxia, high bacterial burden, corrupt matrix, and senescent cells within the wound bed. In WBP we can optimize our therapeutic agents to accelerate endogenous healing or to increase the effectiveness of advanced therapies.

Effects of the basic fibroblast growth factor and its anti-factor in the healing and collagen maturation of infected skin wound

PURPOSE: The infection is one of the main factors that affect the physiological evolution of the surgical wounds. The aim of this work is to evaluate the effects of fibroblast growth factor (FGFâ) and anti-FGFâ in the healing, synthesis and maturation of collagen when topically used on infected skin wounds of rats. METHODS: An experimental study was perfomed in 60 male Wistar rats. All animals were divided in two groups (A and B). Each group was divided in three subgroups A1, B1; A2, B2 and A3, B3. After anesthesia with pentobarbital, two open squared wounds (1cm²), 4cm distant to each other, were done in the dorsal skin of all the rats. In group A (n=30) the wounds were contaminated with multibacterial standard solution, and in group B(n=30) the wounds were maintained sterile. These wounds were named F1 (for inflammation analysis) and F2 (for collagen study). The open wounds of A1 and B1 rats were topically treated with saline solution, A2 and B2 were treated with FGFâ and subgroups A3 and B3 were treated with FGFâ and anti-FGFâ. The rats were observed until complete epitelization of F2 wounds for determination of healing time and the expression of types I and III collagen, using Picro Sirius Red staining. Inflammatory reaction in F1 wounds was studied using hematoxilineosin staining. The three variable was measured by the Image Pro-Plus Média Cybernetics software. The statistical analysis was performed by ANOVA and Tukey test, considering p<0.05 as significant. RESULTS: It was observed that infection retarded significantly (p<0.05) the time of wound scarring and the topical application of FCFb reverted the inhibition of healing caused by bacteria. The inflammatory reaction was greater in the subgroup B2 than in B1 and A3, and the difference was significant (p<0.05). It was observed greater expression of type I collagen in all the subgroups treated with FCFb, when compared with the untreated subgroups. Type III collagen was significantly decreased in wounds of B3 rats, comparing to the other subgroups. CONCLUSIONS: The FCFb accelerated the healing of open infected wounds and contributed with maturation of collagen, enhancing the type I collagen density. The anti-FCFb antibody was able to attenuate the production of both type I and III collagen.

Skin cell isolation and expansion for cell transplantation is limited in patients using tobacco, alcohol, or are exhibiting diabetes mellitus

The aim of this exploratory study was to investigate the isolation and expansion of keratinocytes and fibroblasts from donors with certain medical histories. Biopsies were taken from donors (N=32) falling into one or more of the following categories: a history of heavy smoking and/or alcohol abuse, drug abuse, diabetes mellitus or steroid treatment. Cells from donors who did not fall into any of the above-mentioned categories were used as controls. Proliferation and growth behaviour of cells were analyzed by measurement of passage duration, absorbance (MTT-assay) and light microscopy. Donors with a specific medical history required larger biopsy areas than the control group for isolating a sufficient number of fibroblasts and keratinocytes. Times to confluence were significantly prolonged and absorbances (MTT) were significantly reduced in several donor groups when compared to control cultures. Biopsies from donors with steroid treatment, drug abuse and combined nicotine and alcohol abuse could not be established beyond passage 0 degrees or 1 degree, respectively. We conclude that isolation and expansion of skin cells from donors with certain medical histories may require larger biopsies, prolonged expansion times or may even result in failure. These findings may therefore be of clinical importance in the field of autologous skin cell transplantation.

Enhancement of wound healing by shikonin analogue 93/637 in normal and impaired healing

Wound healing is a complicated biological process, which involves interactions of multiple cell types, various growth factors, their mediators and the extracellular matrix proteins. In this study, we evaluated the effects of shikonin analogue 93/637 (SA), derived from the plant Arnebia nobilis, on normal and hydrocortisone-induced impaired healing in full thickness cutaneous punch wounds in rats. SA (0.1%) was applied topically daily as an ointment in polyethylene glycol base on wounds. SA treatment significantly accelerated healing of wounds, as measured by wound contraction compared to controls in hydrocortisone-impaired animals. SA treatment promoted formation of granulation tissue including cell migration and neovascularization, collagenization and reepithelialization. The expression of basic fibroblast growth factor (bFGF) was higher as revealed by immunohistochemistry in treated wounds compared to controls. However, the expression of transforming growth factor-beta(1) was not affected by SA treatment. Since bFGF is known to accelerate wound healing, the increased expression of bFGF by SA may be partly responsible for the enhancement of wound healing. These studies suggest that SA could be further studied for clinical use to enhance wound healing.

Regulation of wound healing by growth factors and cytokines

Cutaneous wound healing is a complex process involving blood clotting, inflammation, new tissue formation, and finally tissue remodeling. It is well described at the histological level, but the genes that regulate skin repair have only partially been identified. Many experimental and clinical studies have demonstrated varied, but in most cases beneficial, effects of exogenous growth factors on the healing process. However, the roles played by endogenous growth factors have remained largely unclear. Initial approaches at addressing this question focused on the expression analysis of various growth factors, cytokines, and their receptors in different wound models, with first functional data being obtained by applying neutralizing antibodies to wounds. During the past few years, the availability of genetically modified mice has allowed elucidation of the function of various genes in the healing process, and these studies have shed light onto the role of growth factors, cytokines, and their downstream effectors in wound repair. This review summarizes the results of expression studies that have been performed in rodents, pigs, and humans to localize growth factors and their receptors in skin wounds. Most importantly, we also report on genetic studies addressing the functions of endogenous growth factors in the wound repair process.

Cytokine-induced down-regulation of zfm1/splicing factor-1 promotes smooth muscle cell proliferation

One hallmark of inflammation is the proliferation of bystander cells such as vascular smooth muscle cells (SMC), a process governed by growth factors and cytokines. Whereas cytokine induction of gene products promoting inflammation and proliferation is well characterized, little is known about the concomitant down-regulation of potentially counter-regulatory gene products in these cells. By employing the suppression subtractive hybridization-PCR technique, RNA isolated from rat aortic SMC treated with the cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) was subtracted from RNA of control cells. Eleven genes were identified, the expression of which fell by 44-77%. One, the transcriptional repressor splicing factor-1 or zfm1, was characterized further. Antisense oligonucleotide suppression of zfm1 protein synthesis mimicked the stimulatory effects of IL-1 beta and TNF alpha on SMC proliferation and expression of the chemokine MCP-1 and the vascular cell adhesion molecule-1. Moreover, in an in vivo mouse model of atherosclerosis, zfm1 abundance was decreased in proliferating arterial SMC. These findings suggest a role for zfm1 in controlling both proliferation and expression of pro-inflammatory gene products in SMC. Therefore, cytokine-induced down-regulation of zfm1 expression may contribute to the pathogenesis of hyperproliferative inflammatory diseases.

Cyclopentyladenosine improves cell proliferation, wound healing, and hair growth

BACKGROUND

N(6)-Cyclopentyladenosine (CPA), a structural analog of adenosine, is a vasodilator with extensive pharmacological effects. However, little is known about the effect of CPA on wound healing and hair growth.

METHODS

Cellular responses to CPA were measured in vitro by tetrazolium dye reduction and in vivo by bromodeoxyuridine (BrdU) uptake. The effect of CPA on healing of incisional and excisional wounds on the dorsum of diabetic (db/db, n = 94) and nondiabetic (db/+, n = 20) mice and hair growth along the wound margin was evaluated with wound breaking strength, wound closure rate, and quantitative histology.

RESULTS

CPA stimulated proliferation of BALB/3T3 fibroblasts and human dermal microvascular endothelial cells in both quiescent and nonquiescent phases. Wounds treated with CPA at 10 microM showed a significant increase in the number of BrdU-labeled cells, including keratinocytes, fibroblasts, endothelial cells, and cells in sebaceous glands and the outer root sheath of hair follicles, compared with controls (P < 0.05). CPA application (5.1 microg/daily for 12 days) significantly increased the breaking strength of incisional wounds at day 24 postwound (P < 0.05). Excisional wound closure rate in the CPA-treated group (3.4 microg/daily for 15 days) was accelerated starting at day 10 postwound compared with controls (P < 0.01). Tissue sections from CPA-treated wounds showed a sevenfold increase in hair follicle number, compared with controls (P < 0.01). Enhanced hair growth along the wound margin was revealed in CPA-treated groups.

CONCLUSION

CPA stimulated proliferation of many cell types in vivo and in vitro and enhanced wound healing and hair growth. Therefore, CPA could be an interesting candidate for clinical application.

Effects of fibrin glue and growth factors released from platelets on abdominal hernia repair with a resorbable PGA mesh: experimental study

INTRODUCTION

The purpose of this study was to investigate if the strength and quality of an abdominal wall repair with a resorbable PGA (polyglycolic acid) mesh can be improved by fibrin glue or releasates from platelets.

MATERIALS AND METHODS

An abdominal wall defect in the rat was repaired using a PGA mesh in a sublay technique (CG) alone and either with additional fibrin glue (FG) or with platelet releasates (REL). Endpoints were clinical herniation pressure and hydroxyproline concentration (HP) as well as number of fibroblasts and collagen fibers at 7, 14, and 90 days after implantation.

RESULTS

In both experimental groups (REL and FG) higher herniation pressures, hydroxyproline contents, and number of fibroblasts/collagen fibers were found at all times of measurement compared to the CG. The PGA mesh alone showed a significant lack of stability after 14 days which can be compensated for by the investigated components. Significant differences (P < 0.05) were observed regarding the herniation pressure (REL vs CG at 7 and 14 days; FG vs CG at 14 days) and the number of collagen fibers (REL vs CG at 14 days).

CONCLUSIONS

These results suggest that the quality of a PGA mesh repair can be improved by application of fibrin glue or platelet releasates in the described experimental setting.