Establishment of a keloid model in nude mice with human keloid-derived fibroblasts

Objective To establish a simple and efficient method for developing a keloid model in nude mice with human keloid-derived fibroblasts.Methods Twenty-seven female BALB/c nude mice were randomly divided into five groups with 5,5,5,8 and 4 mice in group A,B,C,D and E respectively.The mice in group A,B and C were inoculated with 0.1 ml of suspension containing human keloid-derived fibroblasts at concentrations of 1.0 × 104,3.0 × 104 and 5.0 × 104 per microliter Matrigel,respectively,at the right axillary fossa.The tumors that formed in one mouse in group C were taken out,and cut into several parts measuring 5 mm × 5 mm × 5 mm in size,which were then subcutaneously transplanted into the right axillary fossa of mice in group D.The mice in group E were subcutaneously injected with 100 μl of Matrigel and served as the control group.The formation of tumor in mice was observed by naked eyes,and the size of tumors was measured until day 30 after tumor formation in group A,B and C as well as after tumor transplantation in group D.Mice were sacrificed on day 30 after tumor formation,and histopathologic examination was performed to analyze histological features of transplanted tumors and pathological changes in visceral organs such as heart,liver,spleen,lung and kidney.Results The tumor formation rate was consistently 100％ in group A,B and C,and the time required for tumor formation was (90.20 ± 3.96),(61.00 ± 2.92) and (39.60 ± 3.20) days in group A,B and C respectively.There was a significant difference in tumor volume on the 30th day after tumor formation between group A,B and C ((288.34 ± 25.29) vs.(1 370.63 ± 105.24) vs.(1 940.98 ± 184.37) mm3,F =138.74,P ＜ 0.05).The size of implanted tumor mass in group D firstly increased,then gradually decreased,but began to continuously increase since the 14~ day,and tumor finally formed in 7 out of 8 mice.There was no evidence of tumor formation in group E.Histopathologic examination showed uniform histological manifestations,which were similar to those of human scar,in tumor tissues from mice in group A,B,C and D.Neither pathological changes nor metastases were observed in visceral organs of these mice.Conclusion Keloid-bearing nude mouse model can be established by subcutaneous inoculation with human keloidderived fibroblasts,or by subcutaneous transplantation of tumor masses of a certain size that have formed in nude mice. Key words: Keloid;  Fibroblasts;  Disease models, animal