Pancreas preservation fluid microbial contamination is associated with poor islet isolation outcomes - a multi-centre cohort study

Effect of preservation fluid contamination and associated possible donor-derived infections on early postoperative prognosis in kidney transplant recipients

BACKGROUND

The study aims to analyze the epidemiology of preservation fluid (PF) contamination and investigate the impact of PF contamination and possible donor-derived infections(p-DDI) on early postoperative prognosis in kidney transplant (KT) recipients.

METHODS

A total of 256 PF samples were collected for microbiological evaluation from all KT recipients who received deceased donor donations in our hospital from June 2018 to August 2022. Data on the baseline and clinical characteristics of these PF corresponding to recipients and donors were extracted from the electronic medical record. It mainly included the early postoperative complications and prognosis of KT recipients.

RESULTS

From June 2018 to August 2022, 597 kidney transplants were performed in our center, with 260 recipients receiving kidney transplantation from donation after citizens' death. A total of 256 samples of PF were collected, of which 64.5% (165/256) were culture positive, and 24.6% (63/165) of the culture-positive PF were polymicrobial contamination. A total of 238 strains were isolated, of which coagulase-negative staphylococci (CoNS) had the highest proportion of 34.0% (81/238), followed by Klebsiella pneumoniae with 20.6% (49/238) and Escherichia coli with 8.8% (21/238). Recipients with culture-positive PF had a significantly higher incidence of postoperative infection (55.8% vs. 20.9%, P < 0.001) and DGF (38.2% vs. 24.2%, P = 0.023). In addition, the incidence of p-DDI was 12.9% (33/256). CRKP was the most common pathogen causing p-DDI. The recipients who developed p-DDI had a higher rate of graft loss (9.1% vs. 0.4%, P < 0.001), mortality (12.1% vs. 3.1%, P = 0.018), and longer postoperative hospital stay (30 days (19.5-73.5) vs. (22 days (18-32), P < 0.05) compared with recipients who did not develop p-DDI.

CONCLUSIONS

Culture-positive PF is potentially significant for KT recipients, and p-DDI may increase the risk of poor prognosis for recipients. Prophylactic anti-infective treatment should be actively performed for highly virulent or multidrug-resistant (MDR) pathogens (especially Carbapenem-resistant Klebsiella pneumoniae, CRKP) in PF to avoid the occurrence of p-DDI.

A bioengineered artificial interstitium supports long-term islet xenograft survival in nonhuman primates without immunosuppression

Cell-based therapies hold promise for many chronic conditions; however, the continued need for immunosuppression along with challenges in replacing cells to improve durability or retrieving cells for safety are major obstacles. We subcutaneously implanted a device engineered to exploit the innate transcapillary hydrostatic and colloid osmotic pressure generating ultrafiltrate to mimic interstitium. Long-term stable accumulation of ultrafiltrate was achieved in both rodents and nonhuman primates (NHPs) that was chemically similar to serum and achieved capillary blood oxygen concentration. The majority of adult pig islet grafts transplanted in non-immunosuppressed NHPs resulted in xenograft survival >100 days. Stable cytokine levels, normal neutrophil to lymphocyte ratio, and a lack of immune cell infiltration demonstrated successful immunoprotection and averted typical systemic changes related to xenograft transplant, especially inflammation. This approach eliminates the need for immunosuppression and permits percutaneous access for loading, reloading, biopsy, and recovery to de-risk the use of "unlimited" xenogeneic cell sources to realize widespread clinical translation of cell-based therapies.

The Association of Organ Preservation Fluid Pathogens with Early Infection-Related Events after Kidney Transplantation

(1) Background: The need to elucidate the microbial patterns in preservation fluid and explore their relationship with early infection-related events post kidney transplant and investigate antimicrobial resistance and the effects of preemptive antibiotic therapy. (2) Methods: This retrospective study analyzed the clinical data of 514 kidney transplant donors and 808 recipients from April 2015 to October 2020. Clinical data of donor and recipient characteristics, preservation fluid microbes, early infections (≤30 days), probable donor-derived infections (P-DDIs), antimicrobial resistance and preemptive antibiotic therapy was collected. (3) Results: The incidence of bloodstream (10.3% versus 5.2%, p = 0.006) and graft-site infections (9.7% versus 4.6%, p = 0.004) was significantly higher in recipients with culture-positive preservation fluid. In addition, recipients with ESKAPE pathogens or Candida species had a notably higher rate of bloodstream infections (14.1% versus 6.9%, p = 0.033) and graft-site infections (16.7% versus 3.5%, p < 0.01) than those with other positive pathogens. Preemptive antibiotic therapy decreased the bloodstream infection rate (11.8% versus 35.7%, p = 0.047) when preservation fluid was positive for ESKAPE pathogens. (4) Conclusions: Culture-positive preservation fluid has potential implications for kidney transplant recipients. ESKAPE pathogens or Candida species in preservation fluid as well as their antimicrobial resistance properties and non-preemptive antibiotic therapy could pose a risk of early infection-related events.

Pancreas preservation with amphotericin B deteriorates islet yield for porcine islet isolation

BACKGROUND

Amphotericin B is a crucial agent in the management of serious systemic fungal infections. It is also known to be cytotoxic. In this study, we evaluated the effect of amphotericin B added to the preservation solution on islet yield during islet isolation.

METHODS

Porcine pancreata were preserved in the preservation solution with or without amphotericin B (0.25 μg/mL) for approximately 18 hours at 4°C, and then islet isolation was performed. An optimized number (1750 IE) of isolated islets from each group were transplanted into streptozotocin-induced diabetic mice. The culture of isolated islets and acinar tissue with amphotericin B was also evaluated.

RESULTS

The islet yield before and after purification in the amphotericin B (-) group was significantly higher than that in the amphotericin B (+) group. After islet transplantation into diabetic mice, blood glucose levels reached the normoglycemic range, with 50% and 0% of that of the diabetic mice in the amphotericin B (-) and amphotericin B (+) groups, respectively. In the culture study, amphotericin B was found to be cytotoxic to porcine islets and acinar tissue.

CONCLUSIONS

Amphotericin B added to the preservation solution deteriorates islet yield during porcine islet isolation. Thus, the use of amphotericin B should be considered carefully for the preservation of the pancreas for islet isolation and islet culture before islet transplantation.

Impact of ischemia time on islet isolation success and posttransplantation outcomes: A retrospective study of 452 pancreas isolations

Many variables impact islet isolation, including pancreas ischemia time. The ischemia time upper limit that should be respected to avoid a negative impact on the isolation outcome is not well defined. We have performed a retrospective analysis of all islet isolations in our center between 2008 and 2018. Total ischemia time, cold ischemia time, and organ removal time were analyzed. Isolation success was defined as an islet yield ≥200 000 IEQ. Of the 452 pancreases included, 288 (64%) were successfully isolated. Probability of isolation success showed a significant decrease after 8 hours of total ischemia time, 7 hours of cold ischemia time, and 80 minutes of organ removal time. Although we observed an impact of ischemia time on islet yield, a probability of isolation success of 50% was still present even when total ischemia time exceeds 12 hours. Posttransplantation clinical outcomes were assessed in 32 recipients and no significant difference was found regardless of ischemia time. These data indicate that although shorter ischemia times are associated with better islet isolation outcomes, total ischemia time >12 hours can provide excellent results in appropriately selected donors.

Failure mode and effect analysis in human islet isolation: from the theoretical to the practical risk

This study aimed to assess the global mapping risk of human islet isolation, using a failure mode and effect analysis (FMEA), and highlight the impact of quality assurance procedures on the risk level of criticality. Risks were scored using the risk priority number (RPN) scoring method. The risk level of criticality was made based on RPN and led to risk classification (low to critical). A raw risk analysis and a risk control analysis (with control means and quality assurance performance) were undertaken. The process of human islet isolation was divided into 11 steps, and 230 risks were identified. Analysis of the highest RPN of each of the 11 steps showed that the 4 highest risks were related to the pancreas digestion and islet purification stages. After implementation of reduction measures and controls, critical and severe risks were reduced by 3-fold and by 2-fold, respectively, so that 90% of risks could be considered as low to moderate. FMEA has proven to be a powerful approach for the identification of weaknesses in the islet isolation processes. The results demonstrated the importance of staff qualification and continuous training and supported the contribution of the quality assurance system to risk reduction.

Pancreas collagen digestion during islet of Langerhans isolation-a prospective study

The success of pancreas islet isolation largely depends on donor characteristics, including extracellular matrix composition of which collagen is the main element. We hypothesized that isolation yields are proportional to collagen digestion percentage, and aimed to determine a threshold that predicts isolation success. The amount of pancreas collagen (I-V) was determined using colorimetry prior to and after the digestion process in 52 human islet isolations. Collagen I-V and VI were also assessed histologically. We identified a collagen digestion threshold of ≥ 60% as an independent factor beyond which an islet preparation has a ninefold increased odds of yielding ≥ 250 000 islet equivalents (IEQ) (P = 0.009) and a sixfold increased odds of being transplanted (P = 0.015). Preparations with ≥ 60% collagen digestion (n = 35) yielded 283 017 ± 164 214 IEQ versus 180 142 ± 85 397 in the < 60% collagen digestion group (n = 17) (P = 0.016); respectively 62.9% versus 29.4% of those were transplanted (P = 0.024). Common donor characteristics, initial collagen content, enzyme blend, and digestion times were not associated with collagen digestion percentage variations. Donor age positively correlated with the amount of collagen VI (P = 0.013). There was no difference in islet graft survival between high and low digestion groups. We determined that a 60% pancreas collagen digestion is the threshold beyond which an islet isolation is likely to be successful and transplanted.

Improved harmonization of critical characterization assays across cell therapies

The field of cell therapy has blossomed, providing exciting new options for treating a variety of diseases. While few cell therapy products have US FDA approval, there are thousands of cell treatments at various stages of development, pointing to a potential revolutionary shift in patient care. The expanding number and nature of cellular therapies necessitate greater standardization. Several international organizations are collaborating to pursue some level of global standardization, especially concerning cell banking. However, less harmonization surrounds assays used for critical quality characterization including: identity, purity, safety and potency. Frequently, there is divergence regarding the terms describing the characterization assays across regulatory authorities and guidances. This review summarizes the critical quality assays currently used for different categories of cell therapies. Areas of harmonization and an absence of standardization are highlighted. We propose potential solutions to facilitate harmonization of critical quality characterization assays and the language used to describe them.

Impact of microbial contamination of the islet product during total pancreatectomy with islet autotransplantation

BACKGROUND

The combined use of interleukin-1β and tumor necrosis factor-α blockers in the peritransplant period has improved outcomes of total pancreatectomy with islet autotransplantation (TPIAT). However, these drugs may suppress the immune system, resulting in severe infection.

METHODS

We retrospectively investigated the impact of microbial-contaminated islet product on posttransplant complications and metabolic outcomes of TPIAT patients receiving the IL-1β and TNF-blockade treatment at our center.

RESULTS

Among 108 TPIAT patients, 37 patients (34%) received contaminated products. Preoperative stent treatment and fibrosis score were independent risk factors for the contamination. There were no significant differences between the contaminated and noncontaminated product groups in posttransplant infectious complication rate, length of hospitalization, or readmission rate. However, islet equivalents (P < .0001) and insulin independence rate (P = .036) at 6 months were significantly lower for patients receiving contaminated product.

CONCLUSIONS

These results suggest that combined anti-inflammatory drug use is safe and well tolerated in TPIAT patients who receive contaminated islet product and does not increase the rate of infectious complications; however, contaminated islet product is associated with poor metabolic outcomes.

Early Infectious Complications After Total Pancreatectomy with Islet Autotransplantation: a Single Center Experience

INTRODUCTION

We assessed whether positive microbiological cultures from the islet preparation had any effect on the risk of infectious complications (IC) after total pancreatectomy with islet autotransplantation (TPIAT) in our center.

METHODS

We analyzed preservation fluid and final islet product surveillance cultures with reference to clinical data of patients undergoing TPIAT. All patients received routine prophylactic broad-spectrum antibiotics.

RESULTS

The study involved 10 men and 18 women with a median age of 39 years. Over 30% of surveillance cultures during pancreas processing grew bacterial strains with predominantly polymicrobial contaminations (13 of 22 (59%)). At least one positive culture was identified in almost half of the patients (46%) undergoing TPIAT and a third had both surveillance cultures positive. Infectious complications affected 50% of patients. After excluding cases of PICC line-associated bacteremia/fungemia present on admission, incidence of IC was higher in cases of positive final islet product culture than in those with negative result (57% vs. 21%), which also corresponded with the duration of chronic pancreatitis (p = 0.04). Surgical site infections were the most common IC, followed by fever of unknown origin. There was no concordance between pathogens isolated from the pancreas and those identified during the infection.

CONCLUSIONS

While IC was common among TPIAT patients, we found no concordance between pathogens isolated from the pancreas and those identified during infection. Contamination of the final islet product was of clinical importance and could represent a surrogate marker for higher susceptibility to infection.

Infectious Complications Following Kidney Transplantation-A Focus on Hepatitis C Infection, Cytomegalovirus Infection and Novel Developments in the Gut Microbiota

The incidence of infectious complications, compared with the general population and the pre-transplant status of the recipient, increases substantially following kidney transplantation, causing significant morbidity and mortality. The potent immunosuppressive therapy given to prevent graft rejection in kidney transplant recipients results in an increased susceptibility to a wide range of opportunistic infections including bacterial, viral and fungal infections. Over the last five years, several advances have occurred that may have changed the burden of infectious complications in kidney transplant recipients. Due to the availability of direct-acting antivirals to manage donor-derived hepatitis C infection, this has opened the way for donors with hepatitis C infection to be considered in the donation process. In addition, there have been the development of medications targeting the growing burden of resistant cytomegalovirus, as well as the discovery of the potentially important role of the gastrointestinal microbiota in the pathogenesis of post-transplant infection. In this narrative review, we will discuss these three advances and their potential implications for clinical practice.