Table 1.

β-gal expression in keratinocyte colonies

Samples	Initial colonies		Selected for expansion	Expanded colonies
	Total	% β-gal +	Total	Total	% β-gal +
Pregraft
Submerged culture	256	26.9	24	18	27.8
Organotypic raft culture	131	23.6	24	19	21.1
Graft, weeks
2	408	33.3	ND
5	203	30.0	ND
10	980	23.3	ND
20	353	26.1	ND
40	Insufficient material

Keratinocytes were collected from submerged culture, organotypic culture, and excised grafts and seeded at clonal densities. Two weeks later, the cultures were stained with X-Gal. The percentage of β-gal positive (β-gal +) colonies is noted. A number of colonies from submerged and organotypic cultures were selected and expanded to >10⁷ cells. The percentage of these expanded colonies that were β-gal positive is noted. Colonies from graft tissue were not expanded to >10⁷ cells and this is indicated by ND.