Retinol (Vitamin A1)

Retinol, also known as vitamin A1, is a fat-soluble vitamin in the vitamin A family that is found in food and used as a dietary supplement[1]. Retinol is typically measured in International Units (IU), with 1 IU of retinol equivalent to about 0.3 micrograms[2]. Retinol is transported in plasma, bound to specific transport proteins known as retinol-binding proteins (RBP)[3]. Also known as all-trans retinol, it primarily exerts its effects by activating retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which are part of the nuclear receptor family, regulating gene expression and thereby affecting cell differentiation, proliferation, and death[4].

In vitro, retinol at concentrations of 0.1-3.5µM was added to human embryonic stem cell (hESC) culture media and continuously passaged. 2.0 µM of retinol promoted the proliferation of human embryonic stem cells and induced the expression of specific markers, indicating that retinol has the function of supporting stem cell self-renewal[5]. Retinol increased the expression of the NANOG gene, with its relative expression level increasing by 20 times in the presence of 2.0-3.5 µM retinol[5]. Additionally, retinol maintained the growth of undifferentiated cancer-like stem cells from mouse mammary tumors in long-term culture while eliminating non-CSCs[6]. In addition, 0.1% retinol can effectively treat skin photodamage, promote keratinocyte proliferation and epidermal thickening, thereby alleviating signs of skin aging[7].

References:
Low, J W, Arimond, et al.A food-based approach introducing orange-fleshed sweet potatoes increased vitamin A intake and serum retinol concentrations in young children in rural Mozambique.[J].Journal of Nutrition, 2007.
Shenai J .Vitamin A Supplementation in Very Low Birth Weight Neonates: Rationale and Evidence[J]. 2000.
[3] DeWitt,S,Goodman.PLASMA RETINOL-BINDING PROTEIN[J].Annals of the New York Academy of Sciences, 1980.
[4] Mangelsdorf D J , Umesono K , Kliewer S A ,et al.A direct repeat in the cellular retinol-binding protein type II gene confers differential regulation by RXR and RAR.[J].Cell, 1991, 66(3):555-61.
[5] Rajala K , Vaajasaari H , Suuronen R ,et al.Effects of the physiochemical culture environment on the stemness and pluripotency of human embryonic stem cells[J].Stem Cell Studies, 2011.
[6]Khillan J S .Vitamin A/Retinol and Maintenance of Pluripotency of Stem Cells[J]. Multidisciplinary Digital Publishing Institute, 2014.
[7]Tucker-Samaras S , Zedayko T , Cole C , et al. A stabilized 0.1% retinol facial moisturizer improves the appearance of photodamaged skin in an eight-week, double-blind, vehicle-controlled study[J]. Journal of Drugs in Dermatology, 2009, 8(10):932-936.

视黄醇,也称为维生素A 1 ,是维生素A家族中的一种脂溶性维生素,存在于食物中,用作膳食补充剂[1]。视黄醇通常以国际单位(IU)测量,1 IU的视黄醇相当于大约0.3微克[2]。视黄醇在血浆中转运,与特定的转运蛋白视黄醇结合蛋白(RBP)结合[3]。视黄醇又称全反式视黄醇,它主要通过激活视黄醇酸受体(RARs)和视黄醇酸X受体(RXRs)发挥作用,这些受体是核受体家族的一部分,调控基因表达,进而影响细胞分化、增殖和死亡[4]。

在体外,视黄醇以0.1-3.5µM添加至人胚胎干细胞(hESC)细胞培养基中并进行连续传代培养,2.0 µM的视黄醇促进了人胚胎干细胞的增殖,并诱导了特异性标志物的表达,说明视黄醇具有支持干细胞的自我更新的功能[5]。视黄醇增加了NANOG基因的表达,在2.0-3.5 µM视黄醇存在下,其相对表达水平提高了20倍[5]。视黄醇在长期培养中维持来自小鼠乳腺肿瘤的未分化癌样干细胞的生长,同时消除非CSC[6]。此外,0.1%的视黄醇可以有效治疗皮肤光损伤,促进角质形成细胞增殖和表皮增厚,从而缓解皮肤老化迹象[7]。