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Updated: Aug 14, 2026
In Vitro and In Vivo Assessment of T, B and Myeloid Cells Suppressive Activity and Humoral Responses from Transplant Recipients
Published on: August 12, 2017
Immunologic reaction and viability of cryopreserved homografts
T Fischlein1, A Schütz, M Haushofer
1Department of Cardiac Surgery, University of Munich-Grosshadern Medical Center, Germany.
Insights
Cryopreservation maintains homograft valve viability for aortic valve replacement. Postoperative immunologic reactions were observed but resolved without immunosuppression, especially in ABO-compatible grafts.
Area of Science:
- Cardiovascular Surgery
- Immunology
- Cryobiology
Background:
- Allograft aortic valve replacement using cryopreserved homografts is a common surgical procedure.
- Understanding the immunologic implications of cryopreservation and graft compatibility is crucial for patient outcomes.
Purpose of the Study:
- To investigate the viability of homograft cells after cryopreservation.
- To monitor for immunologic reactions following allograft aortic valve replacement.
- To compare immune responses between ABO-compatible and ABO-incompatible grafts.
Main Methods:
- Morphologic assessment and cell proliferation assays were used to evaluate cell viability post-cryopreservation.
- Prostaglandin I2 release was measured to assess endothelial cell metabolic activity.
- Cytoimmunologic monitoring was conducted daily for 3 weeks post-surgery to assess immune activation.
Main Results:
- Cryopreserved homograft endothelial cells maintained metabolic activity, confirmed by prostaglandin I2 release.
- Cell proliferation assays indicated graft viability post-cryopreservation.
- ABO-incompatible homografts elicited a more intense and prolonged immune activation (activation index 2.1) compared to ABO-compatible grafts (activation index 1.3).
- No immune activation was observed after xenograft valve replacement.
Conclusions:
- Cryopreservation is an effective method for preserving homograft valves, maintaining cell and tissue viability.
- All homograft valves, particularly ABO-incompatible ones, induced reversible postoperative immunologic reactions.
- These reactions resolved spontaneously without the need for immunosuppressive therapy.
Abstract:
Homograft cell viability after cryopreservation was investigated and cytoimmunologic monitoring was performed during the early postoperative course to research possible immunologic reactions after allograft aortic valve replacement. After cryopreservation, morphologic observations were made, a nonradioactive cell proliferation assay was used, and prostaglandin I2 secretion of the remaining endothelial cells was determined. Cytoimmunologic monitoring was performed daily within the first 3 weeks postoperatively. An increase of the activation index greater than 1 was rated as an immunologic reaction. Maintained metabolic activity of graft endothelial cells after cryopreservation was confirmed by prostaglandin I2 release (9.24 +/- 3.48 ng/cm2 basic release and 20.1 +/- 5.76 ng/cm2 when stimulated with 25 mumol/L Na arachidonic acid). Cell proliferation was indicated after graft incubation with the nonradioactive viability kit (0.27 +/- 0.9 at 450 nm). Cytoimmunologic examinations (n = 861) after homograft implantation showed a more intense activation in patients with ABO-incompatible grafts (activation index 2.1 +/- 1.6, n = 16) than in those with ABO-compatible grafts (activation index 1.3 +/- 0.8, n = 17). In these groups, the duration of activation by cytoimmunologic monitoring was 2.8 +/- 1.5 days and 1.3 +/- 0.6 days, respectively (p < 0.041). No activation was observed in 8 patients after xenograft valve replacement (p < 0.01). Our data indicate that cryopreservation of homograft valves represents a cell- and tissue-protective preservation method. Postoperatively, all homograft valves caused immunologic reactions, which were reversible without immunosuppression treatment.
