Immunologic analyses of bovine bone treated with a novel tissue sterilization process.
BACKGROUND
This study evaluates the efficacy of removal of xeno-antigens from bovine bone using a patented BioCleanse process for decellularization of allograft tissues for clinical implantation. BioCleanse deploys a combination of chemicals and several high pressure rinses to achieve standardized sterility assurance levels. This method produces sterile grafts without reducing allograft bone biomechanical properties and effectively removes cells, lipids, and other sources of antigenic material from human allografts for clinical use.


METHODS
In this investigation, BioCleanse is evaluated for its potential in removing xenograft antigens from bovine bone grafts followed by immunologic evaluation in the subcutaneous pouch of immunocompetent rats. The alpha-galactosyl (alpha-gal) epitope with the structure Galalpha1-3Galbeta1-4GlcNAc-R constitutes a critical component of xenoantigens and its removal using BioCleanse from bovine bone was compared with tissue levels of unprocessed bone. The relative degree of antigen removal was also determined through measuring the pro-inflammatory cytokine, tumor necrosis factor (TNF)-alpha, and through the use of histologic grading of cellular infiltrates into bone.


RESULTS
Compact cortical bone inhibited immune cell migration but cancellous bone demonstrated cellular increase and bone resorption in the untreated control group. The alpha-gal xenoantigen level was significantly lower in both cortical (P < 0.001) and cancellous bone (P < 0.001) compared with controls. TNF-alpha levels were significantly (P < 0.001) reduced compared with untreated controls when human acute monocytic leukemia cells were exposed to cortical or cancellous bone.


CONCLUSIONS
BioCleanse effectively removed xenoantigens and inflammatory markers justifying a follow up study in primates to determine these benefits in a model that is primed with preformed xeno-antibodies responsible for hyperacute rejection in hard tissues.
Supronowicz
Peter
P
Biotechnology Developement Department, RTI Biologics Inc., Alachua, FL 32616, USA.
Zhukauskas
Rasa
R
York-Ely
Amanda
A
Wicomb
Winston
W
Thula
Taili
T
Fleming
Laraine
L
Cobb
Ronald R
RR
D000818:Animals; D000941:Antigens / Q000032:analysis* / Q000276:immunology* / Q000302:isolation & purification; D001842:Bone and Bones / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D002417:Cattle; D007118:Immunoassay; D051381:Rats; D013242:Sterilization / Q000379:methods*; D014183:Transplantation, Heterologous / Q000379:methods*; D014312:Trisaccharides / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification
D000941:Antigens; D014312:Trisaccharides; D014409:Tumor Necrosis Factor-alpha; C076569:alpha-galactosyl epitope