Extrinsic Factors Involved in the Differentiation of Stem Cells into Insulin-Producing Cells: An Overview

Table 1

Actions of insulin and glucagon and factors that affect their secretion.

Hormone	Action	Factors affecting secretion
Insulin	Carbohydrate metabolism	Increased secretion
	Increases glucose uptake into target cells (e.g., skeletal and	Increased blood glucose concentration
	adipose tissue cells)
	Stimulates glycogenesis in skeletal muscle and liver	Parasympathetic stimulation following food intake
	Inhibits gluconeogenesis	Increased blood amino acid concentration
	Decreases hepatic output of glucose by	Increased free fatty acid concentration
	inhibiting.gluconeogenesis
	Fat metabolism	Intestinal hormones (e.g., gastrin, cholecystokinin,
		secretin, glucagons-like peptide 1, and glucose-.
		dependent insulinotropic polypeptide)
	Increases fatty acids and triglyceride synthesis by liver	Glucagon
	Increases entry of fatty acids from blood into adipose.	Growth hormone
	tissues
	Inhibits lipolysis, decreasing release of fatty acids from	Cortisol
	adipose tissue
	Protein metabolism	Insulin resistance
	Increases active transport of amino acids into target cells	Obesity
	(e.g., muscle cells)
	Increases protein synthesis	Decreased secretion
	Inhibits protein catabolism	Decreased blood glucose concentration
		Fasting
		Sympathetic stimulation
		Somatostatin
		Leptin
Glucagon	Carbohydrate metabolism	Increased secretion
	Increases glycogenolysis	Decreased blood glucose concentration
	Increases gluconeogenesis	Increased blood amino acid concentration
	Fat metabolism	Increased catecholamines
	Increases lipolysis, making increased amounts of fatty  acids available to the body	Sympathetic stimulation
		Exercise
	Protein metabolism	Decreased secretion
	Increases amino acid uptake by liver cells	Increased blood glucose concentration
	Increases conversion of amino acid to glucose by	Increased blood free fatty acid concentration
	gluconeogenesis in the liver
		Somatostatin
		Insulin