Table 2.

HIV-1 receptor and co-receptor expression in cultured human MSCs

MSC source	Receptor/co- receptor	Technique		Outcome	Reference
		Intracellular	Extracellular
BM-MSCs	CD4	RT-qPCR	Immunocytochemistry on HIV-1 exposed/unexposed cells	Detection of mRNA. Cell surface expression, which increased with HIV-1 exposure.	[117]
		PCR	Flow cytometry	Detection of mRNA. Failure to detect cell surface expression.	[102]
	CCR5		Immunocytochemistry	Low expression on cell surface.	[117]
		RT-PCR	Flow cytometry	Failure to detect mRNA and cell surface expression.	[156]
		RT-qPCR	Immunocytochemistry	Detection of mRNA. Cell surface expression.	[160]
			Immunocytochemistry	Failure to detect cell surface expression.	[162]
		Immunocytochemistry		High expression in cells.	[163]
			Flow cytometry	Cell surface expression on approximately 78% of cells.	[165]
	CXCR4	RT-PCR	Flow cytometry	Failure to detect mRNA. Cell surface expression on 1% of cells. Intracellular expression in 83-98% of cells.	[155]
		RT-PCR	Flow cytometry	Detection of mRNA. Cell surface expression on approximately 26% of cells.	[156]
		RT-PCR	Flow cytometry	Detection of mRNA. Cell surface expression on 43% of cells.	[153]
		RT-qPCR	Immunocytochemistry	Detection of mRNA. Cell surface expression.	[160]
			Immunocytochemistry	Cell surface expression.	[117]
		RT-qPCR	Flow cytometry on 100 ng/mL gp120 treated/untreated cells	Detection of mRNA. Cell surface expression on 84% of cells. Treatment with gp120 upregulated surface expression by 2-3-fold.	[154]
		RT-qPCR	Flow cytometry	Low levels of mRNA. Cell surface expression on approximately 2% of cells.	[186]
		RT-qPCR	Flow cytometry	Detection of mRNA. Cell surface expression on approximately 29.8% of cells.	[168]
		RT-qPCR and flow cytometry	Flow cytometry	Detection of mRNA. Intracellular expression in 95.9% of cells. Cell surface expression on 0.1% of cells.	[169]
			Flow cytometry	Cell surface expression on approximately 96% of cells.	[164]
Preadipocytes (may contain a subset of ASCs)	CD4	RT-PCR		Detection of mRNA.	[32]
		RT-PCR	Immunocytochemistry	Detection of mRNA. Failure to detect cell surface expression.	[33]
		RT-PCR		Failure to detect mRNA.	[34]
	CCR5	RT-PCR		Low levels of mRNA.	[32]
		RT-PCR	Immunocytochemistry	Detection of mRNA. Cell surface expression.	[33]
		RT-PCR		Failure to detect mRNA.	[34]
	CXCR4	RT-PCR		High levels of mRNA.	[32]
		RT-PCR	Immunocytochemistry	Detection of mRNA. Cell surface expression.	[33]
		RT-PCR		Detection of mRNA.	[34]
ASCs	CCR5		Flow cytometry	Negligible cell surface expression.	[167]
	CXCR4		Flow cytometry	Cell surface expression on approximately 1.21% of cells.	[167]
Dermal MSCs	CCR5		Flow cytometry	Negligible cell surface expression.	[167]
	CXCR4		Flow cytometry	Cell surface expression on approximately 1.31% of cells.	[167]
Vessel wall-derived MSCs	CD4	RT-qPCR and flow cytometry	Flow cytometry	Detection of mRNA. Intracellular expression in 20% of cells. Failure to detect cell surface expression.	[101]
	CCR5	RT-qPCR	Flow cytometry	Detection of mRNA. High levels of expression on cell surface.
	CXCR4	RT-qPCR	Flow cytometry	Detection of mRNA. High levels of expression on cell surface.
Fetal blood MSCs	CXCR4	RT-PCR and flow cytometry	Flow cytometry	Detection of mRNA. Cell surface expression on 23-25% of cells. Intracellular expression in 78-83% of cells.	[158]
Fetal BM-MSCs	CXCR4	RT-qPCR and flow cytometry	Flow cytometry	Low levels of mRNA. Cell surface expression on 3.8% of cells. Intracellular expression in 50-90% of cells.	[157]

Abbreviations: ASCs adipose-derived mesenchymal stromal/stem cells, (BM)-MSCs (Bone marrow-derived) mesenchymal stromal/stem cells, CCR5 C-C-motif chemokine receptor type 5, CD4 cluster of differentiation type 4, CXCR4 C-X-C-motif chemokine receptor type 4, gp120 HIV-1 glycoprotein 120, mRNA messenger ribonucleic acid, MSCs mesenchymal stromal/stem cells, PCR polymerase chain reaction, RT-PCR reverse transcription PCR, RT-qPCR reverse transcription quantitative PCR, qPCR quantitative PCR