The in vitro and in vivo effects of Bulbine frutescens and Bulbine natalensis on cutaneous wound healing
In recent years, there has been a growing interest in natural and traditional medicines for the treatment of wounds. Attempts to find agents that promote wound-healing and that are affordable, effective and non-toxic have a long history. In South Africa, hundreds of different indigenous plants are used to treat wounds and burns. The merits of relatively few of these have been scientifically evaluated. Bulbine natalensis and Bulbine frutescens of the Asphodelaceae family are indigenous to southern Africa and are widely used as a skin remedy. This study aimed to investigate the in vitro and in vivo effect of Bulbine natalensis and Bulbine frutescens on cutaneous wound healing. In vitro cell culture study: In vitro studies were carried out on dermal fibroblasts and human keratinocytes cultured under standard conditions using Iscove’s Modified Eagles Medium (MEM) and Dulbecco’s MEM respectively. Confluent cultures of both cell lines were treated with varying concentrations of the leaf extracts of B. frutescens and B. natalensis. These cultures were subjected to the MTT, WST-1 and BrdU assays to determine the cytotoxicity and proliferation effect of the extracts. In addition, migration of cells across a score was analysed over a 48 hour period. In vivo animal study: Excisional and incisional wounds were created on the back of 12 domestic pigs. Mirror imaged wounds were created as control wounds. The excisional wounds were biopsied at days 2, 4, 7, 10 and 16 and the incisional wounds were biopsied at day 16. The rate of closure of the wounds was also recorded. Each excisional wound was analyzed for its biochemical composition by estimating the total amount of protein, DNA, collagen and hexosamine that was present in the wound tissue. The wound healing process was documented histologically (using haematoxylin and eosin and a Mallory’s trichrome stain) and immunohistochemically (using anti- α smooth muscle actin, vascular endothelial growth factor WitsETD and transforming growth factor β receptors I and II). The incisional wounds were used to test tensile strength of the healed wounds using a tensiometer.In the in vitro studies, neither extract caused cytotoxicity to either the fibroblast or keratinocyte cells. Cell proliferation was greater than 100% at 0.1-5 and 100-300 μg/ml for Bulbine natalensis and at 0.1μg/ml for Bulbine frutescens. There was no significant difference in the effects of the two leaf extracts on cell proliferation. The biochemical analysis of the wound tissue showed a significant increase in the collagen, protein and total DNA content of both B frutescens and natalensis treated wounds when compared to the untreated wounds. There was no significant difference in the hexosamine content of both B. frutescens- and B. natalensis-treated and untreated wounds. Analysis of the wound tissue displayed an increase rate of closure of the wound tissue treated with B. frutescens and B. natalensis when compared to the untreated wounds. Full re-epithelialisation of both treated wounds occurred earlier than in the untreated wounds. These findings have important implications for the use of these extracts to treat wound healing.
Thesis (Ph.D.), Faculty of Health Sciences, University of the Witwatersrand, 2009
Bulbine frutescens, Bulbine natalensis, skin wounds, healing