Abstract: The present invention belongs to the technical field of NMN preparation, and particularly relates to a recrystallization method for NMN preparation, comprising the following steps: step 1. preparation of raw materials: preparing nicotinamide, nucleic acid, ribose-5-phosphate and phosphoric acid; step 2. preparation of reaction solution: preparing a suitable buffer, dissolving nicotinamide, ribose, ribose-5-phosphate in the buffer, and adjusting the concentration of the solution; step 3. activated phosphorylation reaction: adding phosphoric acid to the buffer of the dissolved nicotinamide and ribose, and stirring the mixture at appropriate temperature and pH conditions to make reactions take place in the mixture; step 4. addition of enzyme for catalysis; step 5. separation and purification: separating and purifying the reacted mixture to remove unreacted substrates and synthetase.

Abstract: A serum-free complete medium for inducing differentiation of a mesenchymal stem cell to a corneal epithelial cell in the field of differentiation induction of stem cells, prepared by the following method: uniformly mixing the serum-free complete medium, containing 5-10 ?mol of resveratrol, 2-4 ?mol of icariin, 1-3 nmol of aspirin, 1-3 nmol of parathyroid hormone, 5-10 nmol of hydrocortisone, 1-3 mg of rapamycin, 2-10 ?g of testosterone, 2-10 ?g of EPO, 2-10 ?g of LIF and the balance of a corneal epithelial cell serum-free medium in per 1 L; and then performing sterilization by filtration.

Abstract: The present invention belongs to the field of biomedicine, and relates to an inducer for inducing a mesenchymal stem cell to differentiate into an islet cell. An inducer for inducing a mesenchymal stem cell to differentiate into an islet cell consisted of the following components: GLP-1, parathyroid hormone, paracetamol, rapamycin, icariin, trametinib, EPO and VEGF. Each component in a inducer for inducing a mesenchymal stem cell to differentiate into an islet cell of the present invention is safe and non-toxic, requiring fewer steps and short time to induce differentiation, with high induction efficiency.