Dolph Houben

146 CHAPTER 7 Inflammatory response of allotransplant Histology bone slides were scored to quantify the inflammatory response of the allotransplant. We observed significantly (p=0.04) less osteonecrosis on the endosteal surface of the allotransplant in the patent AV bundle group (Fig. 6, Table 2). In addition, we observed significantly less (p=0.02) intramedullary fibrosis and fat necrosis in the patent AV bundle group (Table 2). Both allotransplant groups showed mild patchy infiltration of lymphocytes in the intramedullary space. Using the modified HOES-score, we found the total inflammatory score of bone allotransplants on the endosteal surface to be significantly reduced (p=0.04) in the patent AV bundle group. Thus, significant reduced total inflammatory scores were found due to AV bundle implantation. Table 2: Inflammatory score bone allotransplants on the endosteal surface (H&E slides) Group Percentage of empty endosteal lacunae (%) Osteocyte Score Intramedullary fibrosis Infiltration of lymphocytes Total score (max=9) Patent AV- bundle 11.7 (9.48-12.81) 1 (0-1) 1 (1-1.5) 1 (0.5-1) 3 (2.0-3.0) Ligated AV- bundle 21.65 (13.01-29.64) 1 (1-1.25) 3 (1.75-3) 1 (0.75-1) 5 (3.5-5.25) P-value 0.04* 0.07 0.02* 0.891 0.04* Score system: 0= None, 1= mild ( < 25% of FOI), 2= moderate (25-75% of FOI) 3= severe ( > 75% of FOI) Values are given in mean and SD, field of Interest (FOI),* significant Figure 6 : Histology of bone (Hematoxylin and Eosin staining) showing the normal (contralateral) endosteal morphology of bone (A) compared to the endosteal morphology of the allotransplants (B/C). The lacunae of the allotransplants with a patent arteriovenous (AV) bundle (B) where significantly more occupied by osteocytes compared to the allotransplant in the ligated AV bundle group (C). Demonstrated by the white arrows in C pointing at some of the empty endosteal lacunae. RT-qPCR analyses Analyses of a panel of immunoresponsive mRNA biomarkers in the allotransplant by RT-qPCR showed no statistically significant differences in expression between the two intervention groups compared to the normal (contra-lateral) bone for any of the genes we tested (Fig. 7). Interestingly we did find a statistically significant reduced (p=0.015) expression of IL2 in the patent AV-bundle group (group 1) compared to group 2. The latter result indicates that inflammation was attenuated in this treatment group. Thus, no significant ongoing immune response was observed within the allotransplant 20 weeks after transplantation.