This disclosure generally concerns the fields of cell biology and molecular biology. In particular the invention concerns the field of stem cell biology and maturation of stem cell-derived cardiomyocytes. Disclosed is a method for improving the maturity of stem-cell derived cardiomyocytes, in particular of the ventricular type, as can be witnessed by, for example, an improved upstroke velocity of the stem-cell derived cardiomyocytes.

The present disclosure relates to a composition for promoting the production of stem cell-derived exosomes or increasing the stemness of stem cells. When the composition of the present disclosure is used in culturing stem cells, the stemness of stem cells and the yield of stem cell-derived exosomes are increased, and thus good-quality stem cells and stem cell-derived exosomes can be produced more efficiently, and accordingly, can be advantageously used in related research and development and commercialization.

The present disclosure provides a preparation method of a mesenchymal stem cell (MSC) and an application thereof in a knee product. The additive composition including NOG and quercetin provided by the present disclosure includes components that are combined scientifically and reasonably and play a synergistic role, and has a stable efficacy.

The present disclosure relates, in general, to a media, e.g., a serum replacement, media supplement, complete media or cryopreservation media, comprising a base physiological buffer and liposomes comprising cholesterol, phosphatidylcholine and fatty acids. It is contemplated that media provides advantages to improve cell growth in culture compared to cells cultured not using the serum replacement described herein.

An expression system and process for the production of Diphtheria toxin polypeptides or mutated forms thereof, such as the toxoid CRM197 polypeptide, in genetically-modified E. coli with high yield is described. The system and process is based on the uncoupling of biomass growth from recombinant protein induction, i.e. using an inducer of protein production that cannot be used as a carbon source for growth by the bacteria. The use of specific components and conditions that improve protein yields are also described.

The present invention is drawn to a novel buffer composition comprising a nuclease quenching agent, a stabilizer, a salt, and a cryoprotectant. The present invention is also drawn to a process of producing the composition of the present invention and its utility. The composition of the present invention supports viability of aerobic and anaerobic microbes for extended periods over significant range of temperatures, without the presence of any significant amount of degradants of the constituents of the samples such as biological macromolecules and DNA. The present invention also relates to an economically viable and wide range applications for storage of biological and environmental samples containing microbes.

Provided in the present invention is a cell freezing medium for clinical use. In particular, the cell freezing medium of the present invention comprises the following components: (1) human albumin; (2) cryoprotectant: the cryoprotectant comprises a combination of one or more of dimethyl sulfoxide, glycerol, and ethylene glycol; (3) a saline buffer; wherein the salt buffer is a solution containing Na.sup.+, K.sup.+, Mg.sup.+, Cl.sup., and CH.sub.3COO.sup. ions; (4) a vitamin; and (5) an amino acid, wherein the human albumin concentration is 1%-20% (w/v). The cell, after long-term cryopreservation with the freezing medium of the present invention, has a high viability, and the cellular efficiency maintains a high uniformity. The grade of purity of the freezing medium of the present invention is the pharmaceutical grade or USP grade; and the freezing medium is safe and reliable for clinical use, and can be used or conventional adherent and suspension cells.

The present disclosure provides methods for generating hematopoietic progenitor cells. In some embodiments, the methods involve an in vitro or ex vivo cell culture model utilizing rentionic acid signaling for producing hematopoietic progenitor cells from pluripotent stem cells.

A culture medium for testing drug resistance of H. pylori as well as a preparation method and use thereof are characterized in that 10% to 15% of calf serum, 1.2 mg/mL to 2.4 mg/mL of urea, 0.004 mg/mL to 0.016 mg/mL of phenol red, 10 mol/L to 100 mol/L of nickel chloride and H. pylori selective additive accounting for 1% of the total volume of the culture medium are added on the basis of a Columbia culture medium, and meanwhile, antibiotics for testing drug resistance are added, and the pH value is adjusted to 7.15 to 7.35. The present invention provides a method for a rapid testing of H. pylori resistance in culture media.

Provided is an E. coli cell for the production of a Diphtheria toxin polypeptide or mutated form thereof, such as the toxoid CRM197 polypeptide. The E. coli's endogenous gene encoding leucine/isoleucine/valine transporter subunit (LivK) is disrupted, deleted, or engineered to encode an affinity tag fused to the LivK and/or the E. coli's endogenous gene encoding maltose transporter subunit (MalE) is disrupted, deleted, or engineered to encode an affinity tag fused to the MalE to facilitate purification of the Diphtheria toxin polypeptide or mutated form thereof from the E. coli.