Some aspects of the host response to methacrylic acid containing beads in a mouse air pouch

Exudate analysis indicated that both hydroxamated methacrylic acid-based (HX-MAA) and methacrylic acid-based (MAA) beads without hydroxamation, implanted in an air pouch with gelatin discs, elicited similar biological responses, with both resulting in high cell counts and chemokine (MCP3) levels, relative to control, poly(methyl methacrylate) (PMMA) beads. HX-MAA beads had been used elsewhere to restore homeostatic levels of extracellular matrix degrading enzymes, matrix metalloproteases, whereas the MAA beads (without hydroxamation) promoted angiogenesis in wound healing models. Furthermore, both beads appeared to activate exudate macrophages in the classical manner (high IL12/IL10 ratio) at day 4. Exudate macrophages, which were isolated by a magnetic bead protocol and analyzed by RT-PCR, showed a mixed response: elevated levels of an alternative marker (mannose receptor C type lectin) and a classical marker (IL6) were seen, in macrophages from the HX-MAA and MAA group compared to the PMMA group at day 4. A partial shift to an alternatively activated phenotype was seen by day 10.