Cellular attachment to implanted foreign bodies in relation to tumorigenesis.

Previous experiments demonstrating a reduction of tumorigenicity by roughening the surfaces of plastics implanted in rodents, or by increasing the pore size of cellulose filter implants, were repeated with observations on cellular attachment to these objects and to filters strengthened and made impermeable by bonding to plastic. Round 13-mm discs of methylmethacrylate implanted S.C. in A/BiF/F50 + mice produced sarcomas in 12 percent of mice at 64 weeks. Tumor incidence increased to 60 percent (p less than 0.001) in mice receiving discs to which cellulose filters with pore sizes of 0.025 to 0.1 micrometer were bonded. No tumors occurred with discs covered by 0.45-micrometer filters, followed up to 83 weeks. Vinyl coverslips 15 mm square also produced no sarcomas when covered by 0.45 micrometer filters; plain vinyl produced sarcomas in 40 percent of mice at 64 weeks (p less than 0.001). Sanding of vinyl surfaces reduced tumorigenicity (p less than 0.05). Permeability, fragility, and storage capacity of filters are apparently not related to tumorigenicity. Surface roughness probably is related. Cells, mostly macrophages, were densely and uniformly attached to nontumorigenic surfaces from 24 hr to 2 years after inplantation but were distinctly fewer and not uniformly distrubuted on tumorigenic surfaces. Topology favoring attachment was inherent in 0.45-mum filters and was produced in plastic by gouging irregular excavations 10 to 15 micrometer deep.