Evolution of human kidney allograft pathology diagnostics through 30 years of the Banff classification process

The second half of the previous century witnessed a tremendous rise in the number of clinical kidney transplants worldwide.This activity was,however,accompanied by many issues and challenges.An accurate diagnosis and appropriate management of causes of graft dysfunction were and still are,a big challenge.Kidney allograft biopsy played a vital role in addressing the above challenge.However,its interpretation was not standardized for many years until,in 1991,the Banff process was started to fill this void.Thereafter,regular Banff meetings took place every 2 years for the past 30 years.Marked changes have taken place in the interpretation of kidney allograft biopsies,diagnosis,and classification of rejection and other non-rejection pathologies from the original Banff 93 classification.This review attempts to summarize those changes for increasing the awareness and understanding of kidney allograft pathology through the eyes of the Banff process.It will interest the transplant surgeons,physicians,pathologists,and allied professionals associated with the care of kidney transplant patients.

Urine exosome mRNA-based test for monitoring kidney allograft rejection:Effects of sample transportation and storage,and interference substances

BACKGROUND Exosomes are 30-150 nm nanovesicles with sophisticated nucleic acids cargo,actively secreted by all cells within human body,and found in abundance in all body fluids,including urine.These extracellular vesicles have tremendous potential for next generation diagnostics,theoretically enabling noninvasive assessment of organ and tissue function via liquid biopsy analysis.AIM Recently,feasibility of an exosomal molecular test was demonstrated for postorgan transplant monitoring:Analysis of urine-derived exosomal mRNA cargo allowed early detection of kidney allograft rejection.Here,we further studied urine-derived exosomes and their mRNA content as a highly promising diagnostic modality.This included stability studies of urine samples and exosomal mRNA upon transportation from the point of collection to a centralized testing facility,short-term storage of urine at different conditions upon receipt till the point molecular assay is performed,and effects of various potentially interfering substances on the downstream quantitative polymerase chain reaction(qPCR)assay.METHODS The urine specimens were stored at various conditions and pre-processed in different ways.Next,samples were passed through the columns to capture all extracellular vesicles,the vesicles were lysed to release their content and the exosomal RNA was purified on the mini-columns,reverse transcription was performed,next pre-amplification,followed by a qPCR analysis for a panel of RESULTS To ensure exosomal RNA integrity,the harvested urine specimens should be shipped refrigerated,by overnight delivery.Urine can next be stored at the test site for up to 1 wk at 4°C,and long term should be frozen at-80°C.Urine specimens must be centrifuge at low G-force to deplete cells and debris,to ensure consistent top results in downstream molecular assays.All commonly used medications(tacrolimus,cyclosporin A,mycophenolic acid,everolimus,sirolimus,ascomycin,teriflunomide)were tested and confirmed that they do not cause assay interference.CONCLUSION mRNA from urine-derived exosomes was shown to be stable across a broad range of conditions and produced accurate results when analyzed via qPCR assay for detection of kidney allograft rejection.We identified the most optimal conditions for every step of the process,ensuring pre-analytical sample integrity and robust qPCR results.

Thrombotic microangiopathy after kidney transplantation: Expanding etiologic and pathogenetic spectra

Thrombotic microangiopathy(TMA)is an uncommon but serious complication that not only affects native kidneys but also transplanted kidneys.This review is specifically focused on post-transplant TMA(PT-TMA)involving kidney transplant recipients.Its reported prevalence in the latter population varies from 0.8%to 14%with adverse impacts on both graft and patient survival.It has many causes and associations,and the list of etiologic agents and associations is growing constantly.The pathogenesis is equally varied and a variety of pathogenetic pathways lead to the development of microvascular injury as the final common pathway.PT-TMA is categorized in many ways in order to facilitate its management.Ironically,more than one causes are contributory in PT-TMA and it is often difficult to pinpoint one particular cause in an individual case.Pathologically,the hallmark lesions are endothelial cell injury and intravascular thrombi affecting the microvasculature.Early diagnosis and classification of PT-TMA are imperative for optimal outcomes but are challenging for both clinicians and pathologists.The Banff classification has addressed this issue and has developed minimum diagnostic criteria for pathologic diagnosis of PT-TMA in the first phase.Management of the condition is also challenging and still largely empirical.It varies from simple maneuvers,such as plasmapheresis,drug withdrawal or modification,or dose reduction,to lifelong complement blockade,which is very expensive.A thorough understanding of the condition is imperative for an early diagnosis and quick treatment when the treatment is potentially effective.This review aims to increase the awareness of relevant stakeholders regarding this important,potentially treatable but under-recognized cause of kidney allograft dysfunction.

Emerging role of cell-free DNA in kidney transplantation

Monitoring kidney transplants for rejection conventionally includes serum creatinine,immunosuppressive drug levels,proteinuria,and donor-specific antibody(DSA).Serum creatinine is a late marker of allograft injury,and the predictive ability of DSA regarding risk of rejection is variable.Histological analysis of an allograft biopsy is the standard method for diagnosing rejection but is invasive,inconvenient,and carries risk of complications.There has been a long quest to find a perfect biomarker that noninvasively predicts tissue injury caused by rejection at an early stage,so that diagnosis and treatment could be pursued without delay in order to minimize irreversible damage to the allograft.In this review,we discuss relatively novel research on identifying biomarkers of tissue injury,specifically elaborating on donor-derived cell-free DNA,and its clinical utility.

Efficacy of estradiol on preventing chronic kidney allograft rejection

hronic rejection is the main factor to result in the loss of renal allograft In order to look for a potential therapy chronic rejection, we investigated the efficacy of estradiol on preventing renal chronic rejection The kidneys of female F344 rats were orthotopically transplanted into ovatiectomized female Lewis rats and treated for 16 weeks with either estradiol or vehicle Compared with controls treated with vehicle, estradiol treatment reduced urinary protein excretion, glomerular sclerosis, interstitial infiltration and fibrosis, vascular lesions, in parallel to a reduced ICAM 1 and TGF β mRNA expression Our results suggested that estrodiol could significantly decrease the progression of chronic rejection, at least in female recipients, and the reduced adhesion molecule and TGF β gene expression may be involved in the mechanism for estradiol to prevent chronic rejection