Polymerized Laminin-332 Matrix Supports Rapid and Tight Adhesion of Keratinocytes, Suppressing Cell Migration

Laminin-332 is known to supports the stable anchoring of basal keratinocytes to the epidermal basement membrane but is also a motility factor for wound healing and cancer invasion. Here they investigated Laminin-332 matrices deposited by normal human keratinocytes and many cancer cell lines. All types of cells efficiently deposited Laminin-332 on the culture plates in specific patterns. On the contrary, laminins containing laminin ß1 and/or c1 chains (such as Lm511 and Lm311) were not deposited on the culture plates even if secreted into the culture medium. The deposited Laminin-332 matrix showed a mesh-like network structure as analyzed by electron microscopy, suggesting that Lm332 was highly polymerized. Laminin-332 matrix rather suppressed the migration of keratinocytes as compared with purified Lm332 (not a BioLamina product), which highly promoted cell migration. The Lm332 matrix support adhesion of keratinocytes much more strongly and stably than purified Lm332. Integrin a3ß1 bound to the Lm332 matrix at a three times higher level than purified Lm332. These results indicate that the polymerized Lm332 matrix supports stable cell adhesion whereas unassembled soluble Lm332 supports cell migration. The question is though how the purified Ln-332 looked like. Difficult to purify and might be fractionated.