Advances in mesenchymal stem cell-based therapies for recurrent spontaneous abortion

Table 1 Mechanisms of mesenchymal stem cells improving recurrent spontaneous abortion

Origin	Mechanism	Ref.
Bone marrow	Act locally on CD4+ T cells and macrophages at the maternal-fetal interface	Meng et al[20]
	Inhibit the Th1 immune response and promote the Th2 immune response	Aggarwal and Pittenger[21]
	Promote macrophage polarization to M2-type	Maggini et al[23]
	Immunosuppress TNF-stimulating gene-6	Vallés et al[25]
	Promote paracrine function	Li et al[26]
	Exosomes regulate T cells and macrophages activity	Xiang et al[27]
Adipose	Control the balance of Th1 and Th2 cytokines	Sadighi-Moghaddam et al[30]
	Decrease immunological rejection of paternal antigens by the spleen	Salek Farrokhi et al[31]
	Reduce the infiltration of CD49b+ NK cells into the interface	Rezaei Kahmini et al[32]
	Enhance the balance of angiogenesis	Shahgaldi et al[33]
Wharton’s jelly	Increase expression of Th2 immune factors	Chen et al[38], Ding et al[39]
	Suppress stromal cells and NK cells	Jin et al[40]
Amniotic membrane	Suppress proinflammatory cytokines and control the population of Treg cells	Gan et al[44]
	Enhance angiogenesis and macrophage polarization	Xiao et al[45]
	Stimulate endometrial regeneration and restore the hormone levels	Naeem et al[46]
Decidual	Stimulate angiogenesis	Chen et al[47]
	Increase the proportion of Treg cells and suppress apoptosis and proliferation	Büyükbayrak et al[49]

Th2: T helper type 2; TNF: Tumor necrosis factor; Th1: T helper type 1; NK: Natural killer; Treg: Regulatory T.