Reovirus salvage of squamous cell cancer-contaminated wounds.

Abstract Purpose: To assess rhe susceptibility of human squamous cell carcinoma to reovirus infection in vitro and in vivo using amurine model of cancer-contaminated wounds.Methods: The University of Michigan squamous carcinoma 22B cell line was cultured and inoculated with reovirus In vitro.The effect of the reovirus was assessed with microscopy and a standard 3-(4,5-dimethyi-2-thiazolyl)--2.,5-diphenyl-2H tetra-zolium bromide (MTT) assay. We used the previously established cancer-contaminated wound SCID mouse model to testsaline and reovirus irrigation in vivo. Fifty-five mice were used; 15 were controls., 20 had immediate irrigation, and 20 haddelayed irrigation. Surgical sites were assessed for palpable tumour biweekly.Results: The microscopy and MTT assay both showed evidence of reovirus-mediated squamous cancer cell lysis. The controlmice grew palpable tumours in 80% of the wounds. Immediate irrigation with saline delayed the onset of palpable tumourand demonstrated a persistent reduction in the rate of development of palpable rtJtTiours Ip = .004 compared with controls).This effect disappeared when the saline irrigation was delayed, resulting in a tumour development rate that was not signifi-cantly different from that of the control. Wounds that were irrigated wirh reovirus, both immediately and delayed, did notproduce palpable tumour (p < .0005 when compared with controls).Conclusions: (1) The University of Michigan squamous cell carcinoma 22B cell line is susceptible ro reovirus in vitro. (2)Immediate irrigation with saline resulted in a significant delay in clinically evident tumour growth and a reduction in therate of rumour development in the SCID mouse model. (3) The reovirus irrigation resulted in a significant reduction oftumour development in both the immediate and delayed groups in the SCID mouse model. (4) The efficacy of the reovirusirrigation in the delayed group suggests that the major mechanism of action is through a selective and specific targeting ofimplanted cancer cells.