Non-Invasive Imaging Modalities for Immune Monitoring of Vascularized Composite Allografts Using a Translational Large Animal Model

J. Etra,¹ K. Cilwa,² G. Furtmueller,¹ A. Leto Barone,¹ K. Kolegraff,¹ E. Elster,¹ W. Lee,¹ G. Brandacher.¹

¹Department of Plastic Surgery, Johns Hopkins University School of Medicine, Baltimore, MD
²Naval Medical Research Center, Silver Springs, MD
³Department of Surgery, Uniformed Services, University of Health Sciences and Walter Reed National Military Medical Center, Bethesda, MD.

Meeting: 2018 American Transplant Congress

Abstract number: A42

Keywords: Immunosuppression, Miniature pigs, Non-invasive diagnosis, Screening

Session Information

Session Name: Poster Session A: Biomarkers, Immune Monitoring and Outcomes

Session Type: Poster Session

Date: Saturday, June 2, 2018

Session Time: 5:30pm-7:30pm

Presentation Time: 5:30pm-7:30pm

Location: Hall 4EF

Purpose

Immunological complications and skin rejection remains an obstacle in broadening the applicability of vascularized composite allotransplantation (VCA). Currently, diagnosis of rejection relies on skin biopsies which compromise graft integrity and bears the risk of complications. Non-invasive, optical techniques are a highly attractive alternative to invasive procedures. Combined with computational modeling and machine learning, this technology may provide profiles to allow for improved monitoring and diagnosis of rejection.

Methods:

Heterotopic hind limb transplants were performed in a fully swine leukocyte antigen (SLA) mismatched miniature swine model. No immunosuppression was used in control animals while tacrolimus-based immunosuppression with consecutive withdrawal to induce repeat rejection episodes was administered in a second study group. Multimodal imaging techniques, including infrared (IR) thermography and 3-charge coupled device (3CCD) were used to monitor tissue perfusion and surface oxygenation, respectively to visually and quantitatively monitor the graft. In addition, Raman spectroscopy was used to obtain information about the molecular composition of the skin component.

Results

3CCD imaging results indicate decrease in Red minus Blue channel (R-B) intensity at rejection preceded by a peak in R-B value when compared to contralateral host tissue without immunosuppression. IR thermography imaging shows decreased temperature at rejection preceded by a temperature increase. Graft temperature recovers with immunosuppression. Raman Spectra of rejecting graft skin show changes in spectral signatures suggestive of increased collagen type IV content, possibly attributed to altered tissue composition and thickness facilitating imaging of the epithelial basement membrane.

Conclusion

Non-invasive imaging techniques can detect changes in oxygenation and perfusion of the skin component of VCA. 3CCD and IR thermography demonstrate enhanced contrast during VCA rejection compared to digital imaging. Potential biomarkers of early rejection have been identified via Raman spectroscopy.

CITATION INFORMATION: Etra J., Cilwa K., Furtmueller G., Leto Barone A., Kolegraff K., Elster E., Lee W., Brandacher G. Non-Invasive Imaging Modalities for Immune Monitoring of Vascularized Composite Allografts Using a Translational Large Animal Model Am J Transplant. 2017;17 (suppl 3).

To cite this abstract in AMA style:

Etra J, Cilwa K, Furtmueller G, Barone ALeto, Kolegraff K, Elster E, Lee W, Brandacher G. Non-Invasive Imaging Modalities for Immune Monitoring of Vascularized Composite Allografts Using a Translational Large Animal Model [abstract]. https://atcmeetingabstracts.com/abstract/non-invasive-imaging-modalities-for-immune-monitoring-of-vascularized-composite-allografts-using-a-translational-large-animal-model-2/. Accessed May 8, 2025.

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