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.

Prevention of renal ischemia-reperfusion-induced injury in rats by picroliv.

Picroliv is a potent antioxidant extracted from the roots and rhizome of Picrorhiza kurrooa. It has been shown to impart significant hepatoprotective activities, partly by modulation of free radical-induced lipid peroxidation. Lipid peroxidation and reactive oxygen species are associated with tissue injury in post-ischemic acute renal failure. The efficacy of picroliv was assessed in an in vivo model of renal ischemia-reperfusion injury (IRI) in rats at a dose of 12 mg/kg orally for 7 days. The animals were killed at various times after reperfusion. Increased lipid peroxidation and apoptotic cell number reflected the oxidative damage following renal IRI. Picroliv-pretreated rats exhibited lower lipid peroxidation, improved antioxidant status, and reduced apoptosis, indicating better viability of renal cells. Immunohistochemical studies revealed that picroliv pretreatment attenuated the expression of intercellular adhesion molecule-1 in the glomerular region. These results suggested that picroliv pretreatment protects rat kidneys from IRI, perhaps by modulation of free radical damage and adhesion molecules.

Arnebin-1 accelerates normal and hydrocortisone-induced impaired wound healing.

Wound healing involves inflammation, cell proliferation, matrix deposition, and tissue remodeling. Interaction of different cells, extracellular matrix proteins, and their receptors are mediated by cytokines and growth factors during wound healing. In this study, we have evaluated the effect of arnebin-1, a natural product isolated from Arnebia nobilis, on normal and impaired wound healing in cutaneous punch wound model. Arnebin-1 was applied topically daily on wounds of hydrocortisone-treated or untreated animals. Arnebin-1 significantly accelerated healing of wounds with or without hydrocortisone treatment as revealed by a reduction in the wound width and gap length compared with controls. Arnebin-1 treatment promoted the cell proliferation, migration, and vessel formation to form a thick granulation tissue and re-epithelialization of the wounds. An increase in the synthesis of collagen, fibronectin and transforming growth factor-beta1 was seen in arnebin-1-treated wounds compared with the untreated control. As transforming growth factor-beta1 is known to enhance wound healing, and associated with the wound healing defect in hydrocortisone-treated wounds, the enhanced expression of transforming growth factor-beta1 at both translational and transcriptional level by arnebin-1 may be responsible for the enhancement of wound healing during normal and impaired wound repair. These studies suggest that arnebin-1 could be developed as a potent therapeutic agent for wound healing in steroid-impaired wounds.

Curcumin enhances wound healing in streptozotocin induced diabetic rats and genetically diabetic mice.

Tissue repair and wound healing are complex processes that involve inflammation, granulation and tissue remodeling. Interactions of different cells, extracellular matrix proteins and their receptors are involved in wound healing, and are mediated by cytokines and growth factors. Previous studies from our laboratory have shown that curcumin (diferuloylmethane), a natural product obtained from the rhizomes of Curcuma longa, enhanced cutaneous wound healing in rats and guinea pigs. In this study, we have evaluated the efficacy of curcumin treatment by oral and topical applications on impaired wound healing in diabetic rats and genetically diabetic mice using a full thickness cutaneous punch wound model. Wounds of animals treated with curcumin showed earlier re-epithelialization, improved neovascularization, increased migration of various cells including dermal myofibroblasts, fibroblasts, and macrophages into the wound bed, and a higher collagen content. Immunohistochemical localization showed an increase in transforming growth factor-beta1 in curcumin-treated wounds compared to controls. Enhanced transforming growth factor-beta1 mRNA expression in treated wounds was confirmed by in situ hybridization, and laser scan cytometry. A delay in the apoptosis patterns was seen in diabetic wounds compared to curcumin treated wounds as shown by terminal deoxynucleotidyl transferase-mediated deoxyuridyl triphosphate nick end labeling analysis. Curcumin was effective both orally and topically. These results show that curcumin enhanced wound repair in diabetic impaired healing, and could be developed as a pharmacological agent in such clinical settings.

Acceleration of viral replication and up-regulation of cytokine levels by antimalarials: implications in malaria-endemic areas.

Antimalarial drugs are widely used in malaria endemic areas, both for chemoprophylaxis and also empirically to treat patients presenting with fever. Previously, we have reported that chloroquine enhances the severity of Semliki forest virus (SFV) and encephalomyocarditis virus infection. The studies presented herein show that a broad spectrum of antimalarial drugs augmented the replication of SFV in mice, concomitant with greater tissue damage and up-regulation of mRNA levels of various inflammatory cytokine genes, including interleukin-1 receptor antagonist (IL-1Ra), II-1alpha, IL-1beta, IL-6, IL-12p40, and interferon-gamma inducing factor. Furthermore, chloroquine enhances IL-1Ra production in RAW cells in vitro. Since IL-1Ra is known to be up-regulated in a number of viral infections, we propose that a further enhancement of its expression by antimalarials may be responsible for the increased severity of viral infection in our studies. Thus, the widespread use of antimalarials in malaria-endemic areas may predispose the population to viral infections. Further studies are in progress to delineate mechanism(s) involved in cytokine up-regulation and acceleration of viral replication.

Picroliv modulates the expression of insulin-like growth factor (IGF)-I, IGF-II and IGF-I receptor during hypoxia in rats.

The insulin-like growth factors (IGFs), IGF-I and IGF-II, play important roles in normal growth and differentiation. In recent studies, IGFs have been implicated in tissue repair and regeneration after hypoxicischemic injury. The growth effects of these genes are exerted primarily through IGF-I receptor (IGF-IR). We have earlier shown that picroliv, obtained from the roots of Picrorhiza kurrooa, reduces cellular damage caused by hypoxia in vitro. We have now studied the modulation of IGF-I, IGF-II and IGF-IR in hypoxia and the ability of picroliv to modify their expression in vivo. Male Sprague-Dawley rats, placed in 10% oxygen for 4 days, were sacrificed, and the expression of IGF-I, IGF-II and IGF-IR was determined by immunohistochemistry, in situ hybridization and reverse transcriptase polymerase chain reaction (RT-PCR) in brain, liver and lung. One group of animals was pretreated with picroliv and the other served as control. IGF-I and IGF-IR were expressed in distinct regions of the brain but not in liver or lung. IGF-I was mainly expressed in the hippocampus and cerebellum, whereas IGF-IR expression was also observed in the cortex. A significant reduction in the messenger RNA (mRNA) level of these genes was observed in response to hypoxia. Pretreatment with picroliv not only prevented such downregulation but more importantly resulted in increased levels of IGF-I and IGF-IR. These observations correlated with reduced neuronal cell death observed in these animals. The mRNA of IGF-II was constitutively expressed and was not altered by hypoxia. Modulation of IGF-I and IGF-II expression by picroliv, a novel pharmacological agent, could benefit in similar clinical settings such as myocardial ischemia and certain cerebral injuries.

Enhancement of wound healing by curcumin in animals.

Tissue repair and wound healing are complex processes that involve inflammation, granulation, and remodeling of the tissue. In this study, we evaluated the in vivo effects of curcumin (difeurloylmethane), a natural product obtained from the rhizomes of Curcuma longa on wound healing in rats and guinea pigs. We observed faster wound closure of punch wounds in curcumin-treated animals in comparison with untreated controls. Biopsies of the wound showed reepithelialization of the epidermis and increased migration of various cells including myofibroblasts, fibroblasts, and macrophages in the wound bed. Multiple areas within the dermis showed extensive neovascularization, and Masson's Trichrome staining showed greater collagen deposition in curcumin-treated wounds. Immunohistochemical localization of transforming growth factor-beta1 showed an increase in curcumin-treated wounds as compared with untreated wounds. In situ hybridization and polymerase chain reaction analysis also showed an increase in the mRNA transcripts of transforming growth factor-beta1 and fibronectin in curcumin-treated wounds. Because transforming growth factor-beta1 is known to enhance wound healing, it may be possible that transforming growth factor-beta1 plays an important role in the enhancement of wound healing by curcumin.

Thymosin alpha 1 stimulates endothelial cell migration, angiogenesis, and wound healing.

In wound healing, lymphoid cells release soluble factors that attract fibroblasts and macrophages, initiating repair, endothelial cell migration, angiogenesis, and matrix production. We analyzed the effect of thymosin alpha1 (Talpha1) on endothelial cell migration, angiogenesis, and wound healing. Talpha1, a 28 amino acid peptide initially isolated from the thymus, enhanced the morphologic differentiation of endothelial cells and was a potent chemoattractant for endothelial cells and monocytes in vitro. In vivo, Talpha1 stimulated angiogenesis in a subcutaneous model. When given either topically or i.p., it accelerated wound healing in a punch model, demonstrating that Talpha1 promotes angiogenesis and wound healing.