How old is too old? In vivo engraftment of human peripheral blood stem cells cryopreserved for up to 18 years - implications for clinical transplantation and stability programs

Table 2 Post-CD34 selection characteristics and engraftment data

PBSC unit	Cryopreser-vation (yr)	Post-CD34 selection characteristics					Mouse bone marrow engraftment
		TNC × 103/µL	%Viability	%Purity	BFU-E/105	CFU-GM/106	Mean %CD45	Mean %CD19	Mean %CD3	Mean %CD33
A	18.1	0.3	96	95	19	56	43.4	14.8	1.1	12.6
B	17.7	0.3	94	93	54	85	63.6	20.8	0.4	13.1
C	13.6	2.5	96	98	++	++	10.3	2.8	1	5.6
D	14.6	2.4	95	98	++	++	20.3	6.8	0.5	7.8

TNC: Total nucleated cells; PBSC: Peripheral blood stem cells; BFU: Burst forming units; CFU: Colony forming units; ++: Overgrowth too numerous to count.