Preimplantation renal biopsy: structure does predict function

The Puzzle of Preimplantation Kidney Biopsy Decision-Making Process: The Pathologist Perspective

Kidney transplantation is the best treatment for end-stage renal disease since it offers the greatest survival benefit compared to dialysis. The gap between the number of renal transplants performed and the number of patients awaiting renal transplants leads to a steadily increasing pressure on the scientific community. Kidney preimplantation biopsy is used as a component of the evaluation of organ quality before acceptance for transplantation. However, the reliability and predictive value of biopsy data are controversial. Most of the previously proposed predictive models were not associated with graft survival, but what has to be reaffirmed is that histologic examination of kidney tissue can provide an objective window on the state of the organ that cannot be deduced from clinical records and renal functional studies. The balance of evidence indicates that reliable decisions about donor suitability must be made based on the overall picture. This work discusses recent trends that can reduce diagnostic timing and variability among players in the decision-making process that lead to kidney transplants, from the pathologist's perspective.

Ex vivo confocal microscopy performs real-time assessment of renal biopsy in non-neoplastic diseases

BACKGROUND

Ex vivo confocal microscopy is a technique for tissue examination, which generates images of fresh samples with an optical resolution comparable to those obtained by conventional pathology. The objective of this study was to evaluate the feasibility of using ex vivo confocal microscopy in fusion mode (reflectance and fluorescence) and the H&E-like digital staining that is obtained for the analysis of non-neoplastic kidney biopsies.

METHODS

Twenty-four renal samples acquired from autopsies were scanned in a 4th generation ex vivo confocal microscopy device. The imaging process was completed in an average of three minutes.

RESULTS

Confocal images correlated very well to the corresponding conventional histological sections, both in normal tissue and in chronic lesions (glomerulosclerosis, fibrosis and tubular atrophy). The ex vivo confocal microscopy protocol did not add artifacts to the sample for the ulterior study with light microscopy, nor to the histochemical or immunohistochemical studies.

CONCLUSION

The ease and speed of grayscale and fluorescence image acquisition, together with the quality of the H&E-like digitally stained images obtained with this approach, suggest that this technique shows promise for use in clinical nephrology and renal transplantation.

The prognostic value of frozen section preimplantation graft biopsy in the outcome of renal transplantation

INTRODUCTION

Preimplantation biopsy provides a window on the state of the renal allograft. In this study, the prognostic value of frozen section preimplantation graft biopsy was estimated and compared to regularly processed formalin-fixed biopsy.

MATERIALS AND METHODS

Seventy-four renal allograft recipients were studied. The degree of glomerulosclerosis, acute tubular necrosis, interstitial fibrosis, arteriosclerosis, and arteriolosclerosis was rapidly estimated in frozen sections and correlated to the renal function in the immediate posttransplantation period and 3 months thereafter. The histological changes were also examined in paraffin-embedded sections.

RESULTS

The histological changes observed in rapidly processed frozen sections were comparable to those observed on regularly processed sections and their differences did not reach statistical significance. Glomerulosclerosis and arteriolosclerosis were underestimated, whereas acute tubular necrosis and interstitial fibrosis were overestimated, in the frozen sections compared to permanent ones, but those differences were not statistically significant. Immediate graft function was observed in 45 patients (61%). Delayed graft function was more frequently observed among recipients with donor age above 60 years (57% vs. 32%). Serum creatinine 3 months after transplantation was above 2 mg/dL in 33 recipients (44.5%) and was positively correlated to the degree of tubular necrosis (p = 0.04) and donor age (p = 0.03). Donor age was correlated to the degree of arteriolosclerosis (p < 0.01).

CONCLUSIONS

Frozen section preimplantation biopsy gives reliable information for the situation of the graft that is related to the outcome of renal transplantation.

Novel virtual biopsy of the kidney with near infrared, reflectance confocal microscopy: a pilot study in vivo and ex vivo

PURPOSE

Current diagnostic strategies for the kidney combine noninvasive imaging techniques with invasive procedures such as needle biopsy. However, renal needle biopsy is not devoid of risks, such as bleeding or infection. Additionally, histology studies are limited to ex vivo morphology and processing induces tissue artifacts, is time-consuming and limits the performance of further studies. Near infrared, reflectance CM is a novel technique that allows high resolution optical sectioning through intact tissues without using any exogenous fluorescent stains. Contrast between structures is based on the natural differences in refractivity. In this pilot study we assessed the usefulness of CM in the study of the kidney in vivo and ex vivo.

MATERIALS AND METHODS

Kidneys of live rats were imaged with CM. Contrast in images is based on native properties of the tissue upon being shone with a near infrared laser. By convention hyperrefractile structures are seen as white and hyporefractile structures are seen as black. CM imaging planes varied along the x, y and z axes of space. Images of live kidney were compared with those from ex vivo CM imaging and standard histology procedures.

RESULTS

The tubules, glomeruli, vessels and interstitium were readily identified, revealing intracellular detail. Differences between the kidney in vivo and ex vivo were also observed. Experimental contrast agents further highlighted the nuclei.

CONCLUSIONS

CM is a useful noninvasive imaging technique that is an adjunct to current techniques for 3-dimensional study of the kidney in vivo and ex vivo. Future technical developments will provide key applications during surgical intervention, transplantation and rapid tissue assessment.