Raman-based detection of hydroxyethyl starch in kidney allograft biopsies as a potential marker of allograft quality in kidney transplant recipients

Abstract

In brain-dead donor resuscitation, hydroxyethyl starch (HES) use has been associated with presence of osmotic-nephrosis-like lesions in kidney transplant recipients. Our aim was to determine whether the presence of HES in protocol renal graft biopsies at three months (M3) after transplantation is associated with renal graft quality. According to the HES administered to the donor during the procurement procedure, two groups of patients were defined according graft exposition to HES: HES group, (N = 20) and control group (N = 6). Detection and relative quantification of HES was performed by Raman spectroscopy microimaging on M3 protocol renal graft biopsies. Statistical analyses were used to investigate the association between Raman data and graft characteristics. HES spectral signal was revealed negative in the control group, whereas it was positive in 40% of biopsies from the HES group. In the HES group, a stronger HES signal was associated with a lower risk of graft failure measured by the Kidney Donor Risk Index (KDRI) and was correlated with the allograft kidney function. Thus, HES accumulation in donor kidney, as probed by Raman biophotonic technique, is correlated with the quality of donor kidney and consequently the graft renal function and graft survival.

Figure 1. Flow chart of the study design.

Figure 2. Raman image together with extracted Raman spectra originated from a M3 graft biopsy from the HES group.

(A) Masson trichrome stained section from paraffin-embedded biopsy depicting a renal tubular sections area (x20) (B) 10 μm-thick cryosection of renal graft biopsy observed under white light without staining. Red frame corresponds to the region of interest selected for Raman analysis; red points correspond to spots of Raman measurements (C) Raman image constructed from the integrated intensity on the whole fingerprint spectral range. Color scale: yellow to red corresponding to low to high intensity (D) Spectrum extracted from one pixel (pointed by the blue arrow) (E) Spectra extracted from the selected ROI (red frame).

Figure 3

Relationship between HES spectral signal (arbitrary unit; a.u.) and (A) the Kidney Donor Risk index (KDRI) (r = −0.72; p < 0.001) and (B) estimated glomerular filtration rate at 3 months (eGFR at M3 in ml/min/1.73 m²) (r = 0.88, p < 0.001).