**1. Introduction**

Past decades show an increasing interest in herbal remedies in the public eye, and almost 80% of the population worldwide is now using them as healthcare products [1,2], particularly in developing countries. Sea buckthorn (*Elaeagnus rhamnoides* L.) is a unique medicinal and aromatic plant, frequently used as part of various pharmaceutical treatments, some of which are related to skin care. Sea-buckthorn-derived alcoholic extracts and seed oil were tested for antioxidant, antitumor and regenerative properties [3,4]. Most of these properties are related to its complex structure, rich in flavonoids and essential fatty acids (FA) [5]. Antioxidant activity was suggested as a protectant against different types of irradiation (gamma irradiation [6], UVA and UVB [3]), and, indeed, sea-buckthorn oil treatment showed increased antioxidant protection in irradiated keratinocytes [3]. Antitumor activity of sea-buckthorn-derived products was mostly related to their phenolic compounds [7], mostly by inhibition of fatty acid synthase [8,9]. However, sea-buckthorn

**Citation:** Dudau, M.; Vilceanu, A.C.; Codrici, E.; Mihai, S.; Popescu, I.D.; Albulescu, L.; Tarcomnicu, I.; Moise, G.; Ceafalan, L.C.; Hinescu, M.E.; et al. Sea-Buckthorn Seed Oil Induces Proliferation of both Normal and Dysplastic Keratinocytes in Basal Conditions and under UVA Irradiation. *J. Pers. Med.* **2021**, *11*, 278. https://doi.org/10.3390/ jpm11040278

Academic Editor: Mircea Tampa

Received: 16 March 2021 Accepted: 4 April 2021 Published: 7 April 2021

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seeds and berries are rich in FA [10], which constitute an important percentage of the sea-buckthorn seed oil [5]. It is expected that various FA would contribute to the cellular effects reported in sea-buckthorn-oil-related studies, including effects on skin cells and in animal models.

Normal adult human skin contains a variable dysplastic cell population, which gradually increases with sun exposure [11,12], mostly following UV exposure. These cells are characterized by atypical nuclei and disorganized growth, leading to precancerous skin lesions [13]. Evidence demonstrates that UVA irradiation of dysplastic keratinocytes has detrimental effects in the first few hours of exposure, but long-term, it activates cell protection and survival mechanisms [14], aggravating their malignant potential. Additionally, malignancy was previously shown to be aggravated by alterations in cellular lipid metabolism [15,16] to favor cell survival and proliferation.

Given the paradoxical involvement of FA in health and disease, we investigated whether sea-buckthorn seed oil has regenerative properties for skin cells, in basal conditions as well as under UVA radiation, and if this effect is the same, regardless of the dysplastic nature of the cells. The expression of CD36/SR-B2, a fatty acid translocator, which favors the uptake of fatty acids from the extracellular environment, was also assessed in relationship to UVA exposure.
