MDI 301, a nonirritating retinoid, improves abrasion wound healing in damaged/atrophic skin

Efficacy of 0.2% hyaluronic acid in the healing of skin abrasions in rats

Acute injuries, such as surgical and traumatic, heal normally in an organized and rapid manner. Studies point to the healing activity of hyaluronic acid in all phases of healing. The aim was to evaluate the effectiveness of hyaluronic acid in skin abrasions on the dorsum of rats to compare to usual products on the market. Seventy-two Wistar rats were subjected to excoriation of approximately 2.0 cm2 on the back by dermabrasion. According to the treatment, 3 groups were established: saline, chlorhexidine digluconate and 0.2% hyaluronic acid for 14 days. Animals were photographed on the 2nd, 7th, 10th and 14th postinjury days, and the index of healing of the abrasions was calculated. Biochemically, myeloperoxidase measurements of skin biopsies in addition to histological studies to assess the crust and epidermal layers were performed. The group treated with hyaluronic acid showed better re-epithelialization from the other groups (p < 0.05) on the 7th and 10th days. For the thickness of the crust, the hyaluronic acid group presented thinner crust than other groups on the 10th and 14th days (p < 0.05), but in the epidermis, no difference was observed between the groups studied. All groups showed an increase in myeloperoxidase enzyme on the 2nd day, but a decreasing on the 7th day. On the 10th day, there was a difference in the hyaluronic acid group compared to the other groups (p < 0.05). The application of 0.2% hyaluronic acid significantly accelerated the re-epithelialization of skin abrasions compared to saline and chlorhexidine digluconate.

Healing effects of natural latex serum 1% from Hevea brasiliensis in an experimental skin abrasion wound model

Background

Dermabrasion is related with mechanical and surgical traumas on the skin; usually topical antiseptics and/or saline have been used for healing. Natural products for wound healing can also be used for abrasions, such as latex from Hevea brasiliensis.

Objective

This study aimed to evaluate the in vitro viability and migratory/proliferative effects of latex serum from H. brasiliensis and to compare with a commercially available standard antiseptic solution and saline in experimental dermabrasion on rats.

Methods

For in vitro evaluation, MTT and scratch assays were used. In vivo testing was performed in 72 rats submitted to dermabrasion, treated with saline, antiseptic, or latex serum. This study evaluated re-epithelialization, neutrophilic infiltration, and the quantification of crust and epidermis.

Results

Latex showed viability at 1% and 0.1% concentrations and migratory/proliferative activity at 0.01% concentrations. The re-epithelialization was highest in latex group on 7th day. The latex group displayed lower thickness of crusts and greater extent of epidermal layers. The latex and antiseptic groups showed increases of myeloperoxidase levels on the 2nd day and showed important reductions from the 7th day.

Study limitations

Acute superficial wound model in rats and non-use of gel-cream (medium) without latex.

Conclusion

In conclusion, non-toxic latex stimulated migration/proliferation of keratinocytes in vitro and significantly accelerated wound healing in animal excoriation models compared to chlorhexidine or saline.

Negative pressure wound therapy promoted wound healing by suppressing inflammation via down-regulating MAPK-JNK signaling pathway in diabetic foot patients

AIMS

Negative pressure wound therapy displayed significant clinical benefits in the healing of diabetic foot wounds. In the present study, we investigated the mechanism of regulation of MAPK-JNK (Mitogen-activated protein kinase- c-Jun N-terminal kinase) signaling pathway by negative pressure wound therapy on these wounds.

METHODS

Twenty-six type 2 diabetes patients with foot ulceration were randomly assigned to the two groups, thirteen treated with negative pressure wound therapy and the others treated with traditional debridement therapy. Skin samples were harvested and histologically and immunohistochemical analyzed in both groups. Immunofluorescence stain, Enzyme-linked immunosorbent assay and Western blotting were performed for inducible nitric oxide synthase, inter leukin-6, tumor necrosis factor-α, P-c-Jun N-terminal kinase and c-Jun N-terminal kinase. Real time-polymerase chain reaction was performed to evaluate expression of c-Jun N-terminal kinase, extracellular signal regulated kinase1/2 and p38.

RESULTS

Negative pressure wound therapy could effectively alleviate inflammatory reaction and reduce inter leukin-6 and inducible nitric oxide synthase production after 7 days treatment. The level of tumor necrosis factor-α, inter leukin-6 and P-c-Jun N-terminal kinase were significantly decreased. However, there was no statistical difference in messenger ribonucleic acid expression of p38, extracellular signal regulated kinase1 and 2.

CONCLUSIONS

Negative pressure wound therapy possibly suppress the wound inflammation by inhibiting inter leukin-6, tumor necrosis factor-α and inducible nitric oxide synthase in diabetic foot patients. This effect is maybe mediated at least in part by suppression of Mitogen-activated protein kinase- c-Jun N-terminal kinase signaling pathway.

MDI 301, a synthetic retinoid, depressed levels of matrix metalloproteinases and oxidative stress in diabetic dermal fibroblasts

Diabetic foot ulcerations could result in serious consequences such as amputations. The up-regulation of matrix metalloproteinases and down-regulation of TIMP1 were remarked as distinctive biological characteristics in the diabetic dermal fibroblast. The current study was performed in order to clarify the effect of high glucose on formation of diabetic dermal fibroblast cell. In addition, the effect of MDI 301 on ameliorating diabetic fibroblasts was investigated in this study. The mRNA and protein expression levels of MMPs, TIMP1 and catalase were evaluated against fibroblasts treated with high glucose (30 mM) using qRT-PCR, western blotting and zymography assays. Methods were also employed for investigating the biological effects of MDI 301 on high glucose-induced diabetic fibroblasts. In this study, we found that the unbalance of oxidative stress induced by high glucose concentration play an important role in the formation of diabetic dermal fibroblast from normal cells. In addition, MDI 301, a picolinic acid-substituted ester of 9-cis retinoic acid was employed in this study in order to ameliorate symptoms on diabetic dermal fibroblast induced by high glucose concentration. We found MDI 301 alleviate the effects of high glucose-induced skin damage by balancing the oxidative stress and regulating the MMPs and TIMP1 levels. Our finding indicated that MDI 301 offers the potential for repairing the faulty skin function arising from diabetes.

Calcium alginate enhances wound healing by up-regulating the ratio of collagen types I/III in diabetic rats

Calcium alginate has been proved to favor the skin ulcer healing and collagen synthesis was a critical factor for the wound closure. The present study was to elucidate the mechanism of calcium alginate on the diabetes skin ulceration. Calcium alginate dressing was applied daily on the full-thickness exercising wound created on the back of diabetic rat model as Alg-group (n=6), and the vaseline dressing was used as control (n=6). Rats were respectively sacrificed and the wound tissues were removed and used for the evaluation of various biochemical analysis contained collagen (type I and III) by Western blotting and hydroxyproline level changes by ELISA assay at 3 d, 7 d and 14 d after wounding. The expression of skin collagen I in Alg-group was enhanced from day 3 (0.66 ± 0.25 vs. 0.42 ± 0.09, P<0.05) to day 14 (1.09 ± 0.14 vs. 0.78 ± 0.16, P<0.05). However, no significant difference of collagen III expression was found between two groups during wound healing (P>0.05). And the ratio of collagen I/III in Alg-group was greater than that of Vas-group at day 7 (1.07 ± 0.31 vs. 0.77 ± 0.11, P<0.05) and 14 (1.18 ± 0.30 vs. 0.83 ± 0.14, P<0.05). The hydroxyproline level in skin homogenate of Alg-group was higher than that of Vas-group from day 3 (30.29 ± 0.92 ng/ml vs. 27.52 ± 0.83 ng/ml, P<0.05) to day 14 (89.58 ± 4.97 ng/ml vs. 79.30 ± 4.42 ng/ml, P<0.05). Calcium alginate accelerates the process of wound healing through improving type I collagen synthesis and increasing ratio of collagen I/III in diabetic rats.

MDI 301 suppresses myeloid leukemia cell growth in vitro and in vivo without the toxicity associated with all-trans retinoic acid therapy

MDI 301 is a novel 9-cis retinoic acid derivative in which the terminal carboxylic acid group has been replaced by a picolinate ester. MDI 301, a retinoic acid receptor-α - agonist, suppressed the growth of several human myeloid leukemia cell lines (HL60, NB4, OCI-M2, and K562) in vitro and induced cell-substrate adhesion in conjunction with upregulation of CD11b. Tumor growth in HL60-injected athymic nude mice was reduced. In vitro, MDI 301 was comparable to all-trans retinoic acid (ATRA) whereas in vivo, MDI 301 was slightly more efficacious than ATRA. Most importantly, unlike what was found with ATRA treatment, MDI 301 did not induce a cytokine response in the treated animals and the severe inflammatory changes and systemic toxicity seen with ATRA did not occur. A retinoid with these characteristics might be valuable in the treatment of promyelocytic leukemia, or, perhaps, other forms of myeloid leukemia.

Targeting Matrix Metalloproteinases in Cancer: Bringing New Life to Old Ideas

Since the identification of matrix metalloproteinases (MMPs), a family of zinc-dependent endopeptidases, as being a driving factor for cancer progression and patient prognosis, MMPs have been studied extensively. Although early programs targeting MMPs were largely unsuccessful in clinical trials, they remain a viable and highly desirable therapeutic target based on preclinical studies and their role in disease progression. As information regarding the structure and function of these proteinases is compiled and biotechnology evolves, tools to develop better inhibitors is within our grasp. Improved methods for high throughput screening and in silico drug design programs have identified compounds which are highly potent, have high binding affinities, and exhibit favorable pharmacokinetic profiles. More recently, advances in drug delivery methods or compounds which bind outside the active site have brought new light to the field. In this review, we highlight the role of MMPs in cancer, clinical trials for MMP inhibitors, and novel approaches to targeting MMPs in cancer.

Wound healing efficacy of a chitosan-based film-forming gel containing tyrothricin in various rat wound models

The objective of this study was to evaluate the healing effects of a chitosan-based, film-forming gel containing tyrothricin (TYR) in various rat wound models, including burn, abrasion, incision, and excision models. After solidification, the chitosan film layer successfully covered and protected a variety of wounds. Wound size was measured at predetermined timepoints after wound induction, and the effects of the film-forming gel were compared with negative (no treatment) and positive control groups (commercially available sodium fusidate ointment and TYR gel). In burn, abrasion and excision wound models, the film-forming gel enabled significantly better healing from 1 to 6 days after wound induction, compared with the negative control. Importantly, the film-forming gel also enabled significantly better healing compared with the positive control treatments. In the incision wound model, the breaking strength of wound strips from the group treated with the film-forming gel was significantly increased compared with both the negative and positive control groups. Histological studies revealed advanced granulation tissue formation and epithelialization in wounds treated with the film-forming gel. We hypothesize that the superior healing effects of the film-forming gel are due to wound occlusion, conferred by the chitosan film. Our data suggest that this film-forming gel may be useful in treating various wounds, including burn, abrasion, incision and excision wounds.

The role of nuclear hormone receptors in cutaneous wound repair

The cutaneous wound repair process involves balancing a dynamic series of events ranging from inflammation, oxidative stress, cell migration, proliferation, survival and differentiation. A complex series of secreted trophic factors, cytokines, surface and intracellular proteins are expressed in a temporospatial manner to restore skin integrity after wounding. Impaired initiation, maintenance or termination of the tissue repair processes can lead to perturbed healing, necrosis, fibrosis or even cancer. Nuclear hormone receptors (NHRs) in the cutaneous environment regulate tissue repair processes such as fibroplasia and angiogenesis. Defects in functional NHRs and their ligands are associated with the clinical phenotypes of chronic non-healing wounds and skin endocrine disorders. The functional relationship between NHRs and skin niche cells such as epidermal keratinocytes and dermal fibroblasts is pivotal for successful wound closure and permanent repair. The aim of this review is to delineate the cutaneous effects and cross-talk of various nuclear receptors upon injury towards functional tissue restoration.

Effects of a synthetic retinoid on skin structure, matrix metalloproteinases, and procollagen in healthy and high-risk subjects with diabetes

BACKGROUND

In diabetes, foot ulceration may result from increased skin fragility. Retinoids can reverse some diabetes-induced deficits of skin structure and function, but their clinical utility is limited by skin irritation. The effects of diabetes and MDI 301, a nonirritating synthetic retinoid, and retinoic acid have been evaluated on matrix metalloproteinases (MMPs), procollagen expression, and skin structure in skin biopsies from nondiabetic volunteers and diabetic subjects at risk of foot ulceration using organ culture techniques.

METHODS

Zymography and enzyme-linked immunosorbent assay were utilized for analysis of MMP-1, -2, and -9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) and immunohistochemistry for type I procollagen protein abundance. Collagen structure parameters were assessed in formalin-fixed, paraffin-embedded tissue sections.

RESULTS

The % of active MMP-1 and -9 was higher and TIMP-1 abundance was lower in subjects with diabetes. Type 1 procollagen abundance was reduced and skin structural deficits were increased in diabetes. Three μM MDI 301 reduced active MMP-1 and -9 abundance by 29% (P < .05) and 40% (P < .05), respectively, and increased TIMP-1 by 45% (P = .07). MDI 301 increased type 1 procollagen abundance by 40% (P < .01) and completely corrected structural deficit scores. Two μM retinoic acid reduced MMP-1 but did not significantly affect skin structure.

CONCLUSIONS

These data indicate that diabetic patients at risk of foot ulceration have deficits of skin structure and function. MDI 301 offers potential for repairing this skin damage complicating diabetes.

Cytokeratins 16 and 10 bind to retinoic acid covalently in skin tissue of mice

BACKGROUND

Retinoic acid (RA) has various biological effects in mammalian cells and tissues. In epidermal cells, RA is an inhibitor of differentiation to the squamous phenotype. The molecular mechanisms underlying the effects of RA on epidermal cells and other cell types are mediated by RA nuclear receptors and retinoylation (acylation by RA) of proteins.

OBJECTIVES

To understand the components responsible for RA effects via RA nuclear receptors and retinoylation.

METHODS

We examined for the first time RA-binding proteins in mouse skin in vivo by immunoblotting using anti-RA monoclonal antibodies and identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

RESULTS

We identified eight RA-binding proteins in the skin of hairless mice that were increased by topical RA treatment. Three of these proteins were identified as cytokeratin 10, cytokeratin 16 and serum albumin.

CONCLUSION

These results raise the possibility that RA binding to cytokeratins in vivo may be involved in the effect of RA on keratinocytes in mouse skin.

The Göttingen minipig for assessment of retinoid efficacy in the skin: comparison of results from topically treated animals with results from organ-cultured skin

Göttingen minipigs were treated topically for 6 d with a novel retinoid (MDI 301) at concentrations ranging from 0.3% to 30% in cream vehicle. Treatment of the minipigs did not adversely affect their health (hematological and necropsy parameters) or produce changes in the skin suggestive of retinoid-induced skin irritation. After killing the animals, skin samples from each treatment site were excised and maintained in organ culture for 6 d. In addition, untreated skin was also maintained in organ culture and treated with MDI 301 (0.1-5 microg/ml). After 3 d, the culture supernatants were collected and analyzed for levels of collagen type I and for matrix metalloproteinases (MMPs). Both skin samples treated in vivo and skin samples exposed to MDI 301 in culture demonstrated increased collagen production. Only slight changes in levels of MMP-2 (gelatinase A) or MMP-9 (gelatinase B) were seen. After 6 d, the organ-cultured skin was fixed in formalin and prepared for histology. The organ-cultured skin was compared to skin that was fixed at killing after in vivo treatment. Epidermal hyperplasia was quantified at various MDI 301 concentrations. In vivo and in vitro treatments showed similar results-although the thickness was not substantially changed on average, there were focal areas of hyperplasia at higher retinoid concentrations. Taken together, these data suggest that MDI 301 enhances collagen production in minipig skin, without irritation. Furthermore, these studies suggest that minipig skin exposed to the retinoid in organ culture is equally predictive as topically treated skin. The in vitro organ culture approach may provide a cost-effective alternative model to that of the intact animal for skin retinoid testing.

A combination of curcumin and ginger extract improves abrasion wound healing in corticosteroid-impaired hairless rat skin

Hairless rats were topically treated with a combination of 10% curcumin and 3% ginger extract (or with each agent alone) for a 21-day period. Following this, the rats were treated topically with Temovate (corticosteroid) for an additional 15 days. At the end of the treatment period, superficial abrasion wounds were induced in the treated skin. Abrasion wounds healed more slowly in the skin of Temovate-treated rats than in skin of control animals. Healing was more rapid in skin of rats that had been pretreated with either curcumin or ginger extract alone or with the combination of curcumin-ginger extract (along with Temovate) than in the skin of rats treated with Temovate and vehicle alone. Skin samples were obtained at the time of wound closure. Collagen production was increased and matrix metalloproteinase-9 production was decreased in the recently healed skin from rats treated with the botanical preparation relative to rats treated with Temovate plus vehicle. In none of the rats was there any indication of skin irritation during the treatment phase or during wounding and repair. Taken together, these data suggest that a combination of curcumin and ginger extract might provide a novel approach to improving structure and function in skin and, concomitantly, reducing formation of nonhealing wounds in "at-risk" skin.