Natural dietary antioxidants containing flavonoids modulate keratinocytes physiology: In vitro tri-culture models

Several traditional medicinal herbs are widely used for dermatologic and cosmetic preparations. The beneficial skin repair activity is detected in various phases of wound-healing process, such as cell-cell, cell-matrix interactions or collagen synthesis.

The study assessed the effects of Opuntia ficus-indica (L.) Mill. (Opuntia) and Milk Thistle (MT) (Silybum marianum (L.) Gaerth) on adult keratinocytes (HaCaT) functioning under basal condition or in the presence of mechanical damage (wounded cells).

The role of the natural compounds was tested on HaCaT grown in mono-culture and tri-culture configurations. In tri-cultures models, HaCaT were treated with the conditioned media (CM) obtained by Human Normal Dermal Fibroblast (NHDF) and Human Dermal Microvascular Endothelial cells (HMVEC) co-cultures. Specifically, were tested cell viability, oxidative stress mechanisms (cytokines release and lipid peroxidation) and cellular remodelling (growth factors release or metalloproteinase modulation). Moreover, the migratory potential of HaCaT was analysed by the use of wound healing in vitro assay.

Opuntia and MT differently modified the metabolism (EGF, MMP-9), and the migratory properties of HaCaT both under physiological conditions or upon mechanical damage (wounded cells). Moreover, both compounds modulated HaCaT response to oxidative stress. The response to the natural compounds were modified, and in some cases potentiated, in tri-culture configuration systems.

The data demonstrated that in vitro tri-culture approach is suitable to characterize the role of natural compounds on the complex communication between dermal-epidermal cellular components and microvascular endothelium. Specifically, Opuntia and MT are good alternatives to synthetic compounds in skin repair promotion.