A unified method for different placental products species identification

Background: Placentas are widely used in the production of cosmetics, Chinese medicines, and injections. As the esthetic medicine market grows, challenges such as impure preparations and an increasing number of counterfeit products develop, owing to the lack of standard inspection methods and accurate description of the composition of these products. Objectives: To develop a universal species identification method for placental products. Materials and Methods: Fresh swine, cattle, goat, and frozen human placenta were used as references, while Placenta Hominis and placental extract products from the market as trial samples. Samples were prepared by kit-free DNA isolation, and vertebrate-specific primer sets of mitochondrial 16S and 12S rRNA were used for species-specific region amplification. Direct sequence of amplicons and National Center for Biotechnology Information database comparison was carried for species identification of the testing samples. Results: Trail tests had confirmed the usability of this method. Six of seven Placenta Hominis samples were shown to contain human DNA traces, while the seventh showed no DNA signals belonging to any mammals and a paper-like material underneath the vegetal part, instead of membrane-like placental tissue by visual inspection, suggesting the possibility of counterfeit. Eight injectable and cosmetic placental extract products were tested, and none of them contained analyzable DNA or comparable protein fragments except one, which DNA was from rainbow trout (Oncorhynchus mykiss) rather than sheep, as per the product claim, and was hence misbranded as per the U.S. Food and Drug Administration definition. Conclusion: Our species identification method is easy-to-operate, unified, and resource-saving, which can be applied to different placental products.