Dr Vincent Wong outlines the role of botanical stem cells in skin health and rejuvenation
The incorporation of stem cells into skincare products is, in my opinion, probably the most exciting cosmeceutical revolution that has occurred within the past decade. However, as the idea of applying animal or human cell extracts (even if it is homologous) may seem unappetising to some, scientists have now introduced us to the concept of botanical stem cells. It is important to note, however, that botanical stem cell products do not actually contain stem cells from plants. Instead, the active ingredients are peptides and growth factors extracted from those cells grown in a culture.
The initial development of botanical stem cells in serums and creams began in 2008, with the introduction of extracts taken from the Uttwiler Spätlauber apple, a Swiss varietal developed in the eighteenth century to have an especially long shelf life.1 In a study published in the International Journal for Applied Science,1 the apple stem cell concoction increased in vivo cell turnover and UV resistance, thus indicating a stimulating and protective effect on the human skin.
It is believed that plant stem cell extracts can effectively stimulate collagen synthesis and cell renewal as they contain a 1,000 times higher concentration of antioxidants compared to other botanical extracts.1,2 Many plant stem cell extracts have since been discovered, for example, edelweiss, melon and raspberry. Here, we explore three of the most widely studied botanical stem cell extracts found in serums and creams following the discovery of apple stem cell extracts.
Gotu Kola (centella asiatica)
Gotu kola (centella asiatica) is a small herbaceous plant found in the wetlands of Asia. Centella asiatica (CA) is widely used as a medicinal herb throughout India, China, Indonesia and Africa. Its medicinal uses include the treatment of varicose ulcers, eczema, and psoriasis. The high concentration of pentacyclic triterpenoid found in CA is mainly believed to be responsible for its wide therapeutic actions.2,3
In 2006, Shetty et al investigated the effect of CA in normal and dexamethasone-suppressed wound healing.2 In this study, performed on Wistor albino rats using incision, excision and dead space wound models, CA was found to increase tissue strength significantly compared to controls. Furthermore, CA-treated wounds were also found to epithelialise faster, with a significant increase in wound contraction. Backed by histology findings, CA also showed the ability to overcome the wound-healing suppressing action of dexamethasone.2 Apart from assisting in wound healing, CA also has an effect on melanogenesis.3 In 2005, Park et al conducted a study with results suggesting that asiatic acid (a pentacyclic triterpene found in CA) has the ability to induce apoptosis in human melanoma cells through a series of mediation reactions. Almost a decade later, a study on mouse melanoma conducted by Kwon et al indicated that asiatic acid inhibits microphthalmia-associated transcription factor, a protein that is responsible for regulating melanin synthesising enzymes.4
In terms of skincare and anti-ageing properties, CA extracts exhibit anti-hyaluronidase and anti-elastase activities in the skin.5 Kim et al suggested that CA extracts can also regulate stress-induced premature senescence by preventing repression of DNA replication and mitosis-related gene expression.6 In another study, the effects of CA on human fibroblast cells were assessed.7 The results showed that collagen and fibronectin synthesis were significantly stimulated in the fibroblast cells incubated with CA for 48 hours, further enhanced with the addition of glycolic acid and Vitamins A, C and E. The protective effect of CA on DNA from ultraviolet light-induced damage has also been demonstrated, alongside a reduced expression of inflammation markers (interleukin1-alpha) and a clear densification of collagen network in human papillary dermis.8
Hibiscus (H. sabdariffa)
Hibiscus is a flowering plant that is native to warm-temperate, subtropical and tropical regions of the world. It is used widely in south east Asia for medicinal purposes and is most well known in medicine for its diuretic and anti-hypertensive properties.9 For almost two decades, the effects of hibiscus on tumour cells have been investigated, with study results demonstrating its role as a chemo- preventive agent against tumour promotion.9,10 Recently, Chiu et al studied the effects of hibiscus extract in melanoma cells.11 In this study, hibiscus extract demonstrated the ability to induce autophagic cell death in melanoma cells, indicating the potential of hibiscus extract being developed as an anti-melanoma agent. Hibiscus also plays an important role in wound management. Despite having no antimicrobial properties, hibiscus extract showed significant and dose-dependent wound healing activities, possibly due to its high antioxidant contents and their anti-inflammatory properties.12 Ozkul et al recently published a study that analysed the role of hibiscus extract in UVC exposure in rats. The levels of serum enzymes, renal function tests and some oxidant/antioxidant biomarkers of skin, lens and retina tissues of UVC-exposed rats (four hours daily) were monitored within the study.13 As expected, oxidative stress parameters were escalated after UVC exposure. Interestingly, co-administration of hibiscus extract significantly reversed the levels of these parameters in all tissues.
Grape seeds are extremely rich in polyphenols, secondary plant metabolites which have demonstrated chemo-preventive and/or chemotherapeutic effects in a number of cancer cell cultures and animal models.14 Polyphenols are also well known for their antioxidant, anti-inflammatory and anti-microbial activities. These beneficial biological properties have made grape seed an attractive ingredient for cosmetics and skincare products. Many in vitro studies using dermal fibroblasts or epidermal keratinocytes cell lines have also explored and suggested the inhibition of dermal protease and photoprotective activities of grape seed extracts.15 Grape seed extracts have also been shown to induce vascular endothelial growth factors, thereby accelerating wound healing.16
Exposure to UVB radiation can cause significant cellular DNA damage, resulting in reduced cell viability and apoptosis. In keratocyte cell lines, pre-treatment with grape seed extract for 30 minutes before UVB exposure significantly lowered lipid peroxides levels and DNA photolesions compared to control, thus, increasing cell viability and significantly reducing the number of cells undergoing apoptosis.17 Similar results were also recorded in human studies, where fewer sunburn cells and mutant p53-positive epidermal cells, and more Langerhans cells, were observed in cutaneous areas on the back of volunteers treated with grape seed extract 30 minutes before exposure to two minimal erythema doses of solar simulated radiation.18
Current evidence suggests that grape seed, hibiscus and CA stem cell extracts can play important roles in maintaining skin health. From healing properties to photoprotection and neocollagenesis, botanical stem cells may offer a safe and effective alternative for patients who are uncomfortable with the idea of applying animal or human stem cell products. The potent organic and naturally sourced ingredients mean that exposure to potentially harmful chemicals such as parabens can be avoided. It is important to understand that using botanical stem cell products is not a matter of simple swap (i.e. we are not replacing our skin stem cells with those obtained from plants) – in fact, we are using the growth factors and peptides from botanical stem cells to protect our own tissue and to stimulate our skin cells to be active again. In my opinion, botanical stem cell technology is certainly one of the main directions for future skincare development.
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