Function
Vernix caseosa carries out various physiological functions to assist the fetal extra-uterine adaptation to the environment.
Development of viscera in-utero
The vernix is in direct communication with the amniotic fluid, many of its contents are detached and mixed, which works as a supply to the fetus, as the fetus swallows/breathes the amniotic fluid. Mainly, glutamine (>20% of the amino acids in vernix) functions as a trophic factor for high mitotic-rate cells (e.g., the gastrointestinal tract epithelium, lymphocytes, etc.) as it is needed.[14] Additionally, there is an interaction with the lung’s surfactants to ensure their functionality in maintaining alveolar vacancy.[15]
Skin formation
There are embryological processes for the skin to be cornified (matured) from which desquamation and dehydration of the stratum corneum are facilitated by the decreased pH, as an increased enzymatic activity will initiate.[16] Therefore, the vernix works as a moisturizing and hydrating biofilm in which these processes can be optimized, leading to a softer, healthier fetal skin (i.e., the vernix is approximately 80% water, slowly released).[17]
Thermoregulation
It has been documented in pre-term neonates with underdeveloped epidermis and a high trans-epidermal-water-loss rate (TEWL) to have a subnormal temperature, which could be unsafe for further development (i.e., an increase in the risk of fatality would be present especially and pre-term neonates). However, better prognostic differences are in neonates with the developed hydrophobic layer formed by the vernix were documented. That solidifies an inverse relationship observed between the amount of the vernix and TEWL, which hints to a possible secondary mechanism in thermoregulation.[18]
Antimicrobial defenses
There are different immuno-peptides, enzymes, and lipids found within the vernix that work for the skin flora identification/suppression as the skin is developing, and opportunistic pathogens are trying to break these physical and innate barriers to reach a state of an eruption (disease).[19][20][1]
The immunological molecules include [10][21]:
These molecules work in correspondence with the development of the stratum corneum and the acquired immune system. Alongside, the developmental acidic change in the stratum corneum has been showing a supportive, secondary antimicrobial environment for skin flora and pathogens.[22] As a result, possible future research to utilize the vernix as a prophylactic skin agent against possible infections for those vulnerable, such as in atopic dermatitis patients and bacterial infections.[23] Hence, research implies that maintaining the vernix on infants might decrease the chances of nosocomial infections by an intact epidermal-barrier and the functional immuno-peptides within.[24]
Resolution of wounds and burns
The increase in water percentage, lipids, enzymes, and peptides (e.g., glutamine as a trophic agent) aids in the neonatal wound and burns healing. Therefore, researchers are testing the possibility of applying similar methods to adult wounds and skin-grafting of burns with associate layers of a similar structure as the vernix; moreover, vernix-based topical creams might demonstrate sufficient potency in treating epidermal wounds and augmenting stratum corneum repair and maturation in infants.[25][26]
