Background: Stem cells are of two types: embryonic and adult stem cells and they act as a repair system by replenishing body tissue. Stem cells differentiate into different types of cells, such as neural, hematopoietic, adipose, etc. and are used for the treatment of various conditions like myocardial infarction, spinal cord injury, Parkinson’s disease and diabetes.

Methods: This article focuses on recent research development that addresses the viability issues of stem cells. The efficiency of transplanted stem cells reduces due to conditions like hypoxia, inflammation, nutrient deprivation, immunogenicity, extracellular matrix loss on delivery and mechanical stress.

Results: To increase the viability of stem cells, techniques like scaffolds of stem cells with hydrogel or alginate, pre-conditioning, different routes of administration and encapsulation, are implemented.

Conclusion: For the protection of stem cells against apoptosis, different pathways, namely Phosphoinositide 3-Kinase (PI3K/AKT), Hypoxia-Inducible Factor (HIF1), Mitogen-Activated Protein Kinases (MAPK) and Hippo, are discussed.

Discussion: Activation of the PI3K/AKT pathway decreases the concentration of apoptotic factors, while the HIF pathway protects stem cells against the micro-environment of tissue (hypoxia).

背景：干细胞有两种类型：胚胎干细胞和成体干细胞，它们通过补充身体组织而充当修复系统。干细胞可分化为不同类型的细胞，例如神经细胞，造血细胞，脂肪细胞等，并用于治疗各种疾病，例如心肌梗塞，脊髓损伤，帕金森氏病和糖尿病。

方法：本文重点关注解决干细胞活力问题的最新研究进展。由于缺氧，炎症，营养缺乏，免疫原性，递送时细胞外基质损失和机械应激等情况，移植的干细胞的效率降低。

结果：为了增加干细胞的活力，已实施了诸如干细胞支架，水凝胶或藻酸盐，预处理，不同的给药途径和包封方法等技术。

结论：为了保护干细胞免于凋亡，我们讨论了磷酸肌醇3-激酶（PI3K / AKT），缺氧诱导因子（HIF1），丝裂原激活的蛋白激酶（MAPK）和河马的不同途径。

讨论：PI3K / AKT途径的激活降低了凋亡因子的浓度，而HIF途径保护了干细胞免受组织的微环境（缺氧）的影响。