Optical instrument helps monitor survival rate of patients undergoing liver transplant

Rosa Emilia Moraes, scientific journalist at Linceu Editorial, São José dos Campos, SP, Brasil.

The metabolic stress caused by blood reperfusion is a delicate factor that can lead to the failure of the entire transplant procedure. Risks in the initial perfusion can also irreversibly compromise the organ or graft, causing irreparable damage that results in the patient’s death. Fluorescence spectroscopy under violet light excitation (408 nm) appears to be a viable method for real-time monitoring of the molecular aspect of graft conditions (PANJEHPOUR, et al, 2002).

With the aim of demonstrating the validity of the technique as an adjunct in the indication of an organ or graft viability for transplantation, also considering the conditions presented in the case of a procedure with cold perfusion, the article Fluorescence spectroscopy for clinical transplantation liver grafts monitoring: possibilities offered by 408 nm excitation published in Acta Cirúrgica Brasileira (vol. 37, no. 9) shows the results of research carried out with two major centers of scientific production in Brazil linked to the University of São Paulo (Universidade de São Paulo /USP).

Two graphs with the axes "Fluorescence Intensity (arb. units) x Wavelength (nm). In the first, two lines (532 nm excitation and 408 nm excitation); the first rises and falls abruptly; the second rises and falls more smoothly. In the second, the AF, BT and WR60 lines show similar rises and falls (rises abruptly, falls to almost half, rises a little, falls and stays stable).

Image: article.

Figure 1. Comparison between fluorescence spectra at 532 and 408 nm excitation, with examples of spectra obtained for patient P01. (a) Note the only the band centered around 600 nm is observed for both spectra, whereas 408 nm excitation provides other spectral regions to be analyzed; normalized spectra, indicating the peak absorption wavelengths observed for different stages: endogenous fluorescence (AF) and back-table (BT) stages prior to organ graft implantation, and 60 min after anastomoses finalization (WR60); (b) The main decrease in fluorescence when compared to AF was about 556 nm (green spectral region with intense light absorption by blood constituents).

The transplant procedures were performed at the Special Liver Transplant Unit (Unidade Especial de Transplante de Fígado/UETF), at the General Clinics Hospital of the Faculty of Medicine of Ribeirão Preto (Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto/HC-FMRP-USP), and data analysis was carried out at the Biophotonics Laboratory of the Department of Physics and Materials Science of the São Carlos Institute of Physics (IFSC/USP), funded by the Optics and Photonics Research Center – CEPOF (CePID program/FAPESP) and the INCT of Basic Optics and Applied to Life Sciences (CNPq/FAPESP).

Data collection covered 15 grafts provided exclusively from deceased donors after official and reported brain death following current protocols. The grafts were monitored before and during the transplant stages involving cold perfusion.

Close-up photo of a surgery. One hand holds a cylindrical instrument similar to a thick needle, it has a thread at the top end. Another hand holds a pair of scissors. Both instruments are aimed at an opening in a person's body.

Image: Authors’ personal file.

Different forms of analysis were carried out to identify patterns that would allow the establishment of a risk classification based on a set of alterations observed in the grafts, which could indicate a higher or lower survival rate for patients in the first 30 days after transplant surgery.

The wide variety of responses observed within the limits of the elaborated work did not allow a paradigm to be established, but it demonstrates the potential that the technique presents to enable an instrument that allows the prediction of potential complications immediately after transplantation, such as irreversible post-ischemia damage, risks to metabolic homeostasis, and death. In this way, the authors of this study propose that more research be produced on the subject.

References

PANJEHPOUR, M., et al. Laser-induced fluorescence spectroscopy for in vivo diagnosis of non-melanoma skin cancers. Lasers Surg Med [online]. 2002, vol. 31, no. 5, pp. 367-373 [viewed 18 January 2023]. https://doi.org/10.1002/lsm.10125. Available from: https://onlinelibrary.wiley.com/doi/10.1002/lsm.10125

To read the article, access

VOLLET-FILHO, J.D., et al. Fluorescence spectroscopy for clinical transplantation liver grafts monitoring: possibilities offered by 408 nm excitation. Acta Bras Cir [online]. 2022, vol. 37, no. 9, e370905 [viewed 18 January 2023]. https://doi.org/10.1590/acb370905. Available from: https://www.scielo.br/j/acb/a/Jjtnt9hh8Ny5fDrjJwkbtXc/

External links

Acta Cirúrgica Brasileira – ACB: https://www.scielo.br/acb/

Unidade Especial de Transplante de Fígado (UETF) do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (HC-FMRP-USP): https://cirurgiadigestiva.fmrp.usp.br/setores/unidade-especial-de-transplante-de-figado/

Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto: https://site.hcrp.usp.br/

Departamento de Física e Ciência dos Materiais do Instituto de Física de São Carlos da Universidade de São Paulo: https://www2.ifsc.usp.br/portal-ifsc/fisica-e-ciencia-dos-materiais-fcm/

Centro de Pesquisas em Óptica e Fotônica – CEPOF (programa CePID/FAPESP) / INCT de Óptica Básica e Aplicada às Ciências da Vida (CNPq/FAPESP): https://www.ifsc.usp.br/cepof/

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Como citar este post [ISO 690/2010]:

MORAES, R.E. Optical instrument helps monitor survival rate of patients undergoing liver transplant [online]. SciELO in Perspective | Press Releases, 2023 [viewed ]. Available from: https://pressreleases.scielo.org/en/2023/01/18/optical-instrument-helps-monitor-survival-rate-of-patients-undergoing-liver-transplant/