Overview of the AlloTec® process (Step 1 to 7):
1. Donors are selected after thorough anamnesis and health examination. After approval as a donor, the donor tissue is extracted under controlled conditions by an experienced surgical team in a specific clinic. After extraction and following radiological and clinical examination of the tissue by the responsible surgeon, the femoral head is shipped to C+TBA in a cooled and temperature-monitored package.
2. A range of serological tests are performed, e.g. antibody screening (Ak) and nucleic acid tests (NAT). Where it is not possible to detect the antibodies associated with core and surface antigens of Hepatitis- (HBs, HBc) and HI-viruses (Ag p-24), the NAT method is able to detect the antigens of these viruses.
Hennes:”This takes around 48 to 72 hours. The tissue processing starts only after having assessed the diagnostic findings and final clearance”.
3. After crude removal of surrounding soft tissue, fat and cartilage, the donor tissue is manufactured into its final shape (e.g. blocks, rings, granules). An ultrasonic bath is used to remove blood, cells and tissue components, but mainly to promote the removal of fat from the cancellous structure of the bone, improving the penetration of subsequent substances.
4. The processing is done under cleanroom conditions. The Allotec® process removes any residual fat, denatures non-collagenic proteins, inactivates potential viruses and destroys bacteria. (Depletion of at least 6 log levels).
Cleaning with volatile reagents
“We do not use aggressive chemicals. That’s the major point”, emphasizes Hennes. “This is the main difference between us and other tissue banks. C+TBA uses volatile reagents like ether, alcohol and water for injection (WFI). Because of the characteristics of these reagents and the individual processing steps there is no risk whatsoever that any residues end up in the patient and lead to adverse events.” Cleaning with the AlloTec® process preserves the biomechanical and biological properties related to bone regeneration.
5. During the cleaning process and after treatment with the ultrasonic bath, remaining cells are eluted, non-collagenic proteins are denatured and antigenic and immunogenic potential is reduced. Most notably potential viruses are inactivated and any remaining bacteria are destroyed. The following oxidative treatment denatures persisting soluble proteins, inactivates non-enveloped viruses and bacterial endospores and reduces any potential antigenicity to a minimum, whereas non-soluble collagen remains intact during this step.
6. After the cleaning process with volatile reagents the tissue is lyophilized. During this gentle dehydration technique, frozen tissue water is sublimated from solid phase to gas phase (residual moisture ≤10%, thereby preserving the natural structure of the tissue.
7. After chemical processing, the allograft is double packed and sterilized for a final time by gamma-irradiation (minimum does of 25kGy). This guarantees a pharmaceutical sterility assurance level (SAL) of 10–6 (This means that in one million sales units a maximum of one germ is allowed to be included) and a gentle sterilization of the final product and its packaging without any structural or functional constraints. “Double packing and final sterilization by gamma-irradiation guarantees a 5-year shelf-life at room temperature.” “Only after having received all data regarding the sterilization process and being able to ensure the product sterility, we release the products.”