Cell suspension cultures of allogenic keratinocytes are efficient carriers for ex vivo gene transfer and accelerate the healing of full-thickness skin wounds by overexpression of human epidermal growth factor

Long duration sodium hyaluronate hydrogel with dual functions of both growth prompting and acid-triggered antibacterial activity for bacteria-infected wound healing

Conventional wound dressings are monolithically designed to cover the injured areas as well as absorb the exudates at injured site. Furthermore, antibacterial drugs and growth prompting factors are additionally appended to realize sensible and omnibearing wound management, exhibiting long and tedious treatment process in practice. Consequently, the creation of multifunctional wound dressings that combines wound repair enhancement with antibacterial properties turns out to be significant for simplifying wound managements. In our investigation, electronegative human epidermal growth factor (hEGF) was combined with the positively charged Zn-Al layered double hydroxides (Zn-Al LDHs) via electrostatic interaction while the obtained hEGF/LDH was integrated with sodium hyaluronate hydrogel (SH) hydrogel, forming a composite hydrogel with synergistic benefits for wound management. The innovative hEGF/LDH@SH hydrogel equipped with fine biocompatibility was designed to optimize wound healing in which hEGF stimulates epithelial cell growth while LDH released antibacterial factor Zn2+ against Methicillin-resistant staphylococcus aureus (MRSA) and Escherichia coli (E.coli) under acidic wound environment. Additionally, the SH hydrogel constructed a three-dimensional structure that not only safeguarded the wound area but also maintained a moist environment conducive to recovery. The synthesized hEGF/LDH was confirmed via fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermo-gravimetry (TG) measurements. The release of Zn2+ from Zn-Al LDH under acid circumstance was detected via inductively coupled plasma (ICP) and the in vitro bactericidal experiments endowed the antibacterial property of hEGF/LDH@SH hydrogel. In vitro drug release experiments illustrated the controlled-release of hEGF from hEGF/LDH which promoted the long-term affect of hEGF at wound site. In vitro cell experiments verified that the hEGF/LDH@SH hydrogel motivated the promotion on cell proliferation and migration without cytotoxicity. An in vivo study of the repairing of MRSA-infected wound in mice indicated that hEGF/LDH@SH hydrogel serves as a simple and novel, innoxious and efficient wound healing approach. This brand new hydrogel possesses properties of promoting the regeneration of skin tissue, achieving antimicrobial therapy without any accessional antibacterial drugs as well as realizing controlled release of hEGF.

Overexpression of pEGF improved the gut protective function of Clostridium butyricum partly through STAT3 signal pathway

Clostridium butyricum (C. butyricum) is a probiotic that could promote animal growth and protect gut health. So far, current studies mainly keep up with the basic biological functions of C. butyricum, missing the effective strategy to further improve its protective efficiency. A recent report about C. butyricum alleviating intestinal injury through epidermal growth factor receptor (EGFR) inspired us to bridge this gap by porcine epidermal growth factor (EGF) overexpression. Lacking a secretory overexpression system, we constructed the recombinant strains overexpressing pEGF in C. butyricum for the first time and obtained 4 recombinant strains for highly efficient secretion of pEGF (BC/pPD1, BC/pSPP, BC/pGHF, and BC/pDBD). Compared to the wild-type strain, we confirmed that the expression level ranges of the intestinal development-related genes (Claudin-1, GLUT-2, SUC, GLP2R, and EGFR) and anti-inflammation-related gene (IL-10) in IPECs were upregulated under recombinant strain stimulation, and the growth of Staphylococcus aureus and Salmonella typhimurium was significantly inhibited as well. Furthermore, a particular inhibitor (stattic) was used to block STAT3 tyrosine phosphorylation, resulting in the downregulation on antibacterial effect of recombinant strains. This study demonstrated that the secretory overexpression of pEGF in C. butyricum could upregulate the expression level of EGFR, consequently improving the intestinal protective functions of C. butyricum partly following STAT3 signal activation in IPECs and making it a positive loop. These findings on the overexpression strains pointed out a new direction for further development and utilization of C. butyricum. KEY POINTS: • By 12 signal peptide screening in silico, 4 pEGF overexpression strains of C. butyricum/pMTL82151-pEGF for highly efficient secretion of pEGF were generated for the first time. • The secretory overexpression of pEGF promoted the intestinal development, antimicrobial action, and anti-inflammatory function of C. butyricum. • The overexpressed pEGF upregulated the expression level of EGFR and further magnified the gut protective function of recombinant strains which in turn partly depended on STAT3 signal pathway in IPECs.

Gene Therapy and its Application in Dermatology

Gene therapy is an experimental technique to treat genetic diseases. It is based on the introduction of nucleic acid with the help of a vector, into a diseased cell or tissue, to correct the gene expression and thus prevent, halt, or reverse a pathological process. It is a promising treatment approach for genetic diseases, inherited diseases, vaccination, cancer, immunomodulation, as well as healing of some refractory ulcers. Both viral and nonviral vectors can be used to deliver the correct gene. An ideal vector should have the ability for sustained gene expression, acceptable coding capacity, high transduction efficiency, and devoid of mutagenicity. There are different techniques of vector delivery, but these techniques are still under research for assessment of their safety and effectiveness. The major challenges of gene therapy are immunogenicity, mutagenicity, and lack of sustainable therapeutic benefit. Despite these constraints, therapeutic success was obtained in a few genetic and inherited skin diseases. Skin being the largest, superficial, easily accessible and assessable organ of the body, may be a promising target for gene therapy research in the recent future.

Re-epithelialization of adult skin wounds: Cellular mechanisms and therapeutic strategies

Cutaneous wound healing in adult mammals is a complex multi-step process involving overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodelling. Re-epithelialization describes the resurfacing of a wound with new epithelium. The cellular and molecular processes involved in the initiation, maintenance, and completion of epithelialization are essential for successful wound closure. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here, we focus on cellular mechanisms underlying keratinocyte migration and proliferation during epidermal closure. Inability to re-epithelialize is a clear indicator of chronic non-healing wounds, which fail to proceed through the normal phases of wound healing in an orderly and timely manner. This review summarizes the current knowledge regarding the management and treatment of acute and chronic wounds, with a focus on re-epithelialization, offering some insights into novel future therapies.

Advances in surgical applications of growth factors for wound healing

Growth factors have recently gained clinical importance for wound management. Application of recombinant growth factors has been shown to mimic cell migration, proliferation, and differentiation in vivo, allowing for external modulation of the healing process. Perioperative drug delivery systems can enhance the biological activity of these growth factors, which have a very short in vivo half-life after topical administration. Although the basic mechanisms of these growth factors are well understood, most have yet to demonstrate a significant impact in animal studies or small-sized clinical trials. In this review, we emphasized currently approved growth factor therapies, including a sustained release system for growth factors, emerging therapies, and future research possibilities combined with surgical procedures. Approaches seeking to understand wound healing at a systemic level are currently ongoing. However, further research and consideration in surgery will be needed to provide definitive confirmation of the efficacy of growth factor therapies for intractable wounds.

Allogeneic keratinocyte for intractable chronic diabetic foot ulcers: A prospective observational study

Chronic diabetic foot ulcers (DFUs) are a common problem in patients with diabetes and are often difficult to treat. The application of newly developed dressing material in patients with chronic DFUs has been reported to be effective. The purpose of this study was to evaluate the usefulness of allogeneic keratinocyte treatment for chronic DFUs. We performed weekly allogeneic keratinocyte treatment for up to 12 weeks in 71 patients with intractable DFUs. We investigated healing rate, wound-healing velocity, and time to 50% wound size reduction and analysed factors affecting ulcer healing. Fifty-six patients (78.8%) had complete wound healing. Forty-six patients (64.7%) showed complete healing within an average of 6.1 weeks, and 10 patients (14.1%) showed partial healing with an average 35.5% reduction vs initial size at the end of follow up. The 10 patients who showed partial healing continued to receive treatment after the 12-week study period. The mean time to complete wound healing was 7.8 weeks. Fifteen patients (21.1%) experienced treatment failure because of infection, local necrosis, no change in ulcer size, or osteomyelitis during the follow-up period. No adverse events were observed. Allogeneic keratinocyte treatment is effective for chronic, difficult-to-treat DFUs.

Immunomodulation as Rescue for Chronic Atonic Skin Wounds

Chronic skin wounds, caused by arterial or venous insufficiency or by physical pressure, constitute an increasing medical problem as populations age. Whereas typical wounds are characterized by local inflammation that participates in the healing process, atonic wounds lack inflammatory markers, such as neutrophil infiltration, and generally do not heal. Recently, prominent roles in the immunopathology of chronic wounds were attributed to dysregulations in specific cytokines, chemokines, matrix metalloproteinases (MMPs), and their substrates. Together with the complement system, these molecular players provide necessary defense against infections, initiate angiogenesis, and prepare tissue reconstitution. Here, we review the current state of the field and include the concept that, aside from surgery and stem cell therapy, healing may be enhanced by immunomodulating agents.

The promotion function of Berberine for osteogenic differentiation of human periodontal ligament stem cells via ERK-FOS pathway mediated by EGFR

Coptidis Rhizoma binds to the membrane receptors on hPDLSC/CMC, and the active ingredient Berberine (BER) that can be extracted from it may promote the proliferation and osteogenesis of periodontal ligament stem cells (hPDLSC). The membrane receptor that binds with BER on the cell surface of hPDLSC, the mechanism of direct interaction between BER and hPDLSC, and the related signal pathway are not yet clear. In this research, EGFR was screened as the affinity membrane receptor between BER and hPDLSC, through retention on CMC, competition with BER and by using a molecular docking simulation score. At the same time, the MAPK PCR Array was selected to screen the target genes that changed when hPDLSC was simulated by BER. In conclusion, BER may bind to EGFR on the cell membrane of hPDLSC so the intracellular ERK signalling pathways activate, and nuclear-related genes of FOS change, resulting in the effect of osteogenesis on PDLSC.

The anti-tumor effect of intravesical administration of normal urothelial cells on bladder cancer

BACKGROUND AIMS

Urothelial bladder cancer (UBC) is the second most common cancer of the genitourinary tract and for advanced forms of the disease it has a high mortality rate. There are no approved new molecularly targeted agents or chemotherapeutics for advanced UBC beyond cisplatin-based chemotherapy except the recently approved anti-programmed death ligand 1 (anti-PD-1/PD-L1) antibody. With complex genetic and epigenetic alterations in tumors, despite several druggable targets identified, to cure UBC is still a challenging unmet medical need. Like other cancers, UBC to the host body is considered as a wound, aging stem cell disease and immunosuppressive disorder. Therefore, we proposed a novel cellular approach to target the host body by intravesical instilling of normal urothelial cells that could repair the injury and reduce inflammation by activating body-reparative capacity and because non-self cells are transplanted, host body immune responses could be induced in the tumor microenvironment of UBC to restrain and even eliminate tumor cells.

METHODS

In this study, we isolated and expanded normal male murine urothelial cells and intravesically administered them into the bladders of female mice of two orthotopic bladder tumor models and one urothelial injury model.

RESULTS

We showed that the instillation of normal urothelial cells containing stem/progenitor cell population into bladders could have anti-tumor effect in orthotopic tumor models, possibly by activating immune responses and helping injured urothelium tissue recovery in a chemically induced urothelial injury model.

CONCLUSIONS

Our findings could lead to an innovative and revolutionary cell therapy modality with normal urothelial cells as an effective and safe therapeutic option for UBC.

Tissue engineering and surgery: from translational studies to human trials

Tissue engineering was introduced as an innovative and promising field in the mid-1980s. The capacity of cells to migrate and proliferate in growth-inducing medium induced great expectancies on generating custom-shaped bioconstructs for tissue regeneration. Tissue engineering represents a unique multidisciplinary translational forum where the principles of biomaterial engineering, the molecular biology of cells and genes, and the clinical sciences of reconstruction would interact intensively through the combined efforts of scientists, engineers, and clinicians. The anticipated possibilities of cell engineering, matrix development, and growth factor therapies are extensive and would largely expand our clinical reconstructive armamentarium. Application of proangiogenic proteins may stimulate wound repair, restore avascular wound beds, or reverse hypoxia in flaps. Autologous cells procured from biopsies may generate an ‘autologous’ dermal and epidermal laminated cover on extensive burn wounds. Three-dimensional printing may generate ‘custom-made’ preshaped scaffolds – shaped as a nose, an ear, or a mandible – in which these cells can be seeded. The paucity of optimal donor tissues may be solved with off-the-shelf tissues using tissue engineering strategies. However, despite the expectations, the speed of translation of in vitro tissue engineering sciences into clinical reality is very slow due to the intrinsic complexity of human tissues. This review focuses on the transition from translational protocols towards current clinical applications of tissue engineering strategies in surgery.

Reactive oxygen species and bacterial biofilms in diabetic wound healing

Chronic wounds are a common and debilitating complication for the diabetic population. It is challenging to study the development of chronic wounds in human patients; by the time it is clear that a wound is chronic, the early phases of wound healing have passed and can no longer be studied. Because of this limitation, mouse models have been employed to better understand the early phases of chronic wound formation. In the past few years, a series of reports have highlighted the importance of reactive oxygen species and bacterial biofilms in the development of chronic wounds in diabetics. We review these recent findings and discuss mouse models that are being utilized to enhance our understanding of these potentially important contributors to chronic wound formation in diabetic patients.

Gene delivery in tissue engineering and regenerative medicine

As a promising strategy to aid or replace tissue/organ transplantation, gene delivery has been used for regenerative medicine applications to create or restore normal function at the cell and tissue levels. Gene delivery has been successfully performed ex vivo and in vivo in these applications. Excellent proliferation capabilities and differentiation potentials render certain cells as excellent candidates for ex vivo gene delivery for regenerative medicine applications, which is why multipotent and pluripotent cells have been intensely studied in this vein. In this review, gene delivery is discussed in detail, along with its applications to tissue engineering and regenerative medicine. A definition of a stem cell is compared to a definition of a stem property, and both provide the foundation for an in-depth look at gene delivery investigations from a germ lineage angle.

Expression and effects of epidermal growth factor on human periodontal ligament cells

Repair of damaged periodontal ligament (PDL) tissue is an essential challenge in tooth preservation. Various researchers have attempted to develop efficient therapies for healing and regenerating PDL tissue based on tissue engineering methods focused on targeting signaling molecules in PDL stem cells and other mesenchymal stem cells. In this context, we investigated the expression of epidermal growth factor (EGF) in normal and surgically wounded PDL tissues and its effect on chemotaxis and expression of osteoinductive and angiogenic factors in human PDL cells (HPDLCs). EGF as well as EGF receptor (EGFR) expression was observed in HPDLCs and entire PDL tissue. In a PDL tissue-injured model of rat, EGF and IL-1β were found to be upregulated in a perilesional pattern. Interleukin-1β induced EGF expression in HPDLCs but not EGFR. It also increased transforming growth factor-α (TGF-α) and heparin-binding EGF-like growth factor (HB-EGF) expression. Transwell assays demonstrated the chemotactic activity of EGF on HPDLCs. In addition, EGF treatment significantly induced secretion of bone morphogenetic protein 2 and vascular endothelial growth factor, and gene expression of interleukin-8 (IL-8), and early growth response-1 and -2 (EGR-1/2). Human umbilical vein endothelial cells developed well-formed tube networks when cultured with the supernatant of EGF-treated HPDLCs. These results indicated that EGF upregulated under inflammatory conditions plays roles in the repair of wounded PDL tissue, suggesting its function as a prospective agent to allow the healing and regeneration of this tissue.

Gene therapy for skin diseases

The skin possesses qualities that make it desirable for gene therapy, and studies have focused on gene therapy for multiple cutaneous diseases. Gene therapy uses a vector to introduce genetic material into cells to alter gene expression, negating a pathological process. This can be accomplished with a variety of viral vectors or nonviral administrations. Although results are promising, there are several potential pitfalls that must be addressed to improve the safety profile to make gene therapy widely available clinically.

Clinical Impact Upon Wound Healing and Inflammation in Moist, Wet, and Dry Environments

SIGNIFICANCE

Successful treatment of wounds relies on precise control and continuous monitoring of the wound-healing process. Wet or moist treatment of wounds has been shown to promote re-epithelialization and result in reduced scar formation, as compared to treatment in a dry environment.

RECENT ADVANCES

By treating wounds in a controlled wet environment, delivery of antimicrobials, analgesics, other bioactive molecules such as growth factors, as well as cells and micrografts, is allowed. The addition of growth factors or transplantation of cells yields the possibility of creating a regenerative wound microenvironment that favors healing, as opposed to excessive scar formation.

CRITICAL ISSUES

Although several manufacturers have conceived products implementing the concept of moist wound healing, there remains a lack of commercial translation of wet wound-healing principles into clinically available products. This can only be mitigated by further research on the topic.

FUTURE DIRECTIONS

The strong evidence pointing to the favorable healing of wounds in a wet or moist environment compared to dry treatment will extend the clinical indications for this treatment. Further advances are required to elucidate by which means this microenvironment can be optimized to improve the healing outcome.

A new technique of ex vivo gene delivery of VEGF to wounds using genetically modified skin particles promotes wound angiogenesis

BACKGROUND

Transplantation of genetically modified keratinocytes has been shown to accelerate wound healing. However, this method is labor-intensive and time-consuming. We have developed a new technique of intraoperative gene delivery to wounds that involves transplantation of transfected minced skin particles (MSPs) derived from harvested partial-thickness skin.

STUDY DESIGN

MSPs measuring 0.8 × 0.8 × 0.35 mm were created from a split-thickness skin graft of a pig. In vitro transfection was carried out with adenoviral LacZ (Ad-LacZ) for qualitative and adenoviral vascular endothelial growth factor (Ad-VEGF) for quantitative analysis. Transfected MSPs were transplanted to each of 2.5 × 2.5 cm full-thickness wounds on the dorsum of the pig. Nontransfected MSPs served as controls. Wound chambers were applied and injected with saline to create a wet environment.

RESULTS

LacZ expression was detected in migrating cells originating from MSPs both in vitro and in vivo. VEGF expression in the wound fluid of Ad-VEGF-MSP-transplanted wounds on each of days 2 to 4 (mean ± SEM 6.74 ± 1.89 ng/mL, day 2; 9.88 ± 2.27 ng/mL, day 3; 9.87 ± 1.28 ng/mL, day 4) was significantly higher (p < 0.0001) compared with wounds transplanted with either untransfected MSPs, Ad-LacZ-MSPs, or untransplanted controls. In vitro VEGF expression was significantly higher (p < 0.0001) in Ad-VEGF 1 × 10(10) transfected MSPs compared with either Ad-VEGF 1 × 10(9) transfected MSPs or untransfected MSPs. Wounds transplanted with Ad-VEGF-MSPs showed significantly higher (p < 0.0001) numbers of newly formed blood vessels (12.6 ± 0.9 vessels/high power field [HPF]) compared with wounds transplanted with either Ad-LacZ-MSPs (4.4 ± 0.5 vessels/HPF) or untransfected MSPs (5.2 ± 0.7 vessels/HPF). All MSP-transplanted wounds (Ad-VEGF-MSPs, untransfected MSPs, Ad-LacZ-MSPs) showed significantly higher re-epithelialization compared with untransplanted wounds on days 10 and 14 (p < 0.0001).

CONCLUSIONS

We demonstrated successful transfection of MSPs that can be transplanted to wounds as a source of gene-expressing cells. This technique can be used to deliver growth-modulating genes in wound healing.

Anti-apoptotic role of EGF in HaCaT keratinocytes via a PPARbeta-dependent mechanism

Epidermal growth factor (EGF) plays an important role in epithelial cell proliferation and apoptosis. Our recent studies found that EGF-attenuated tumor necrosis factor-alpha induced HaCaT keratinocyte apoptosis, and this effect was accompanied by up-regulation of the expression of peroxisome proliferator-activated receptor beta (PPARbeta). However, little is known about whether PPARbeta is functionally involved in the inhibition of keratinocyte apoptosis by EGF. Here, we showed that EGF up-regulated the DNA-binding and transcriptional regulation activities of PPARbeta. Antisense phosphorothioate oligonucleotides against PPARbeta markedly inhibited de novo synthesis of PPARbeta and attenuated the protective effect of EGF on tumor necrosis factor-alpha-induced apoptosis. L165041, a specific PPARbeta ligand, significantly enhanced the transcriptional regulation activity of PPARbeta and increased the protective effect of EGF. These results suggest a molecular mechanism by which EGF protects HaCaT keratinocytes against apoptosis in a PPARbeta-dependent manner.

Cell suspensions of autologous keratinocytes or autologous fibroblasts accelerate the healing of full thickness skin wounds in a diabetic porcine wound healing model

Autologous dermal fibroblasts may be useful in the treatment of diabetic skin wounds. We hypothesized that cultured fibroblasts or cultured keratinocytes would not only survive in a hyperglycemic wound environment but also enhance the rate of re-epithelialization. We previously developed a new porcine model of delayed cutaneous wound healing in the diabetic pig. Full thickness wounds were created on the dorsum and dressed with polyurethane chambers to keep the wounds wet and to allow for wound fluid monitoring. Suspensions of either autologous fibroblasts or autologous keratinocytes were injected into full thickness wounds and compared with wounds treated in a wet environment in normal saline. Serum glucose and wound fluid glucose concentrations were monitored daily. Wound contraction was monitored and biopsies taken on day 12. Transplantation of suspensions of autologous fibroblasts or autologous keratinocytes enhanced re-epithelialization of cutaneous full thickness wounds. Wounds treated with autologous fibroblasts showed a re-epithelialization rate of 86.75% and wounds treated with autologous keratinocytes showed a re-epithelialization rate of 91.3%. This is compared with a re-epithelialization rate of 56.8% seen in the normal saline treated wounds. While previous studies have shown fibroblasts suspension to have little effect in the treatment of full thickness wounds in nondiabetic wounds, this study shows a clear beneficial effect in the use of fibroblast or keratinocyte suspensions for the cutaneous healing of diabetic wounds in pigs.