Systematic review of preservation solutions for allografts for liver transplantation based on a network meta-analysis

Evaluation of a Novel Graft-Holding Solution in Hair Transplantation: A Randomized Controlled Clinical Study

BACKGROUND

Hair transplantation has become a popular choice for alopecia treatment; however, postsurgical hair shedding still annoys both patients and surgeons.

OBJECTIVE

To explore the impact of graft-holding solution on postsurgical hair shedding and testify the protective efficacy of histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine (HTK-AD).

METHODS

There were 240 patients enrolled in the study, and the follicles were placed into either HTK-AD or Ringer solution (RS). Masson staining and live/dead staining were performed to evaluate graft morphology and apoptosis levels, respectively. The between-group comparison of postsurgical graft shedding, survival rate, complications, and patient satisfaction was performed.

RESULTS

Grafts in HTK-AD maintained organized dense collagen construction and higher cell viability, but those preserved in RS became soft, which hindered implantation. Histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine significantly reduced the incidence of postsurgical hair shedding (73.81% vs 95%), delayed shedding onset, and diminished shedding amount versus RS ( p < .05) when ≥3,000 grafts were transplanted. The shedding duration was shortened, and hair regrowth started earlier in HTK-AD versus RS ( p < .05); thus, satisfaction was increased. The final survival rate showed no difference between 2 groups.

CONCLUSION

Histidine-tryptophan-ketoglutarate solution with adenosine triphosphate and deferoxamine is superior to RS for hair graft preservation because it improves graft viability and alleviates postsurgical shedding.

Abdominal Organ Preservation Solutions in the Age of Machine Perfusion

The past decade has been the foreground for a radical revolution in the field of preservation in abdominal organ transplantation. Perfusion has increasingly replaced static cold storage as the preferred and even gold standard preservation method for marginal-quality organs. Perfusion is dynamic and offers several advantages in comparison with static cold storage. These include the ability to provide a continuous supply of new metabolic substrates, clear metabolic waste products, and perform some degree of organ viability assessment before actual transplantation in the recipient. At the same time, the ongoing importance of static cold storage cannot be overlooked, in particular when it comes to logistical and technical convenience and cost, not to mention the fact that it continues to work well for the majority of transplant allografts. The present review article provides an overview of the fundamental concepts of organ preservation, providing a brief history of static cold preservation and description of the principles behind and basic components of cold preservation solutions. An evaluation of current evidence supporting the use of different preservation solutions in abdominal organ transplantation is provided. As well, the range of solutions used for machine perfusion of abdominal organs is described, as are variations in their compositions related to changing metabolic needs paralleling the raising of the temperature of the perfusate from hypothermic to normothermic range. Finally, appraisal of new preservation solutions that are on the horizon is provided.

Changing liver utilization and discard rates in clinical transplantation in the ex-vivo machine preservation era

Liver transplantation is a well-established treatment for many with end-stage liver disease. Unfortunately, the increasing organ demand has surpassed the donor supply, and approximately 30% of patients die while waiting for a suitable liver. Clinicians are often forced to consider livers of inferior quality to increase organ donation rates, but ultimately, many of those organs end up being discarded. Extensive testing in experimental animals and humans has shown that ex-vivo machine preservation allows for a more objective characterization of the graft outside the body, with particular benefit for suboptimal organs. This review focuses on the history of the implementation of ex-vivo liver machine preservation and how its enactment may modify our current concept of organ acceptability. We provide a brief overview of the major drivers of organ discard (age, ischemia time, steatosis, etc.) and how this technology may ultimately revert such a trend. We also discuss future directions for this technology, including the identification of new markers of injury and repair and the opportunity for other ex-vivo regenerative therapies. Finally, we discuss the value of this technology, considering current and future donor characteristics in the North American population that may result in a significant organ discard.

Gut Microbiota-Derived l-Histidine/Imidazole Propionate Axis Fights against the Radiation-Induced Cardiopulmonary Injury

Radiation-induced cardiopulmonary injuries are the most common and intractable side effects that are entwined with radiotherapy for thorax cancers. However, the therapeutic options for such complications have yielded disappointing results in clinical applications. Here, we reported that gut microbiota-derived l-Histidine and its secondary metabolite imidazole propionate (ImP) fought against radiation-induced cardiopulmonary injury in an entiric flora-dependent manner in mouse models. Local chest irradiation decreased the level of l-Histidine in fecal pellets, which was increased following fecal microbiota transplantation. l-Histidine replenishment via an oral route retarded the pathological process of lung and heart tissues and improved lung respiratory and heart systolic function following radiation exposure. l-Histidine preserved the gut bacterial taxonomic proportions shifted by total chest irradiation but failed to perform radioprotection in gut microbiota-deleted mice. ImP, the downstream metabolite of l-Histidine, accumulated in peripheral blood and lung tissues following l-Histidine replenishment and protected against radiation-induced lung and heart toxicity. Orally gavaged ImP could not enter into the circulatory system in mice through an antibiotic cocktail treatment. Importantly, ImP inhibited pyroptosis to nudge lung cell proliferation after radiation challenge. Together, our findings pave a novel method of protection against cardiopulmonary complications intertwined with radiotherapy in pre-clinical settings and underpin the idea that gut microbiota-produced l-Histidine and ImP are promising radioprotective agents.

Organ Preservation Solutions in Transplantation: A Literature Review

OBJECTIVES

Renal transplant with ABO-incompatible donors expands the donor pool. Earlier studies have focused the use of protocol biopsies in ABOincompatible transplant patients. Our study described outcomes of indication (for cause) renal biopsies and clinical outcomes in patients with ABO-incompatible renal transplant.

MATERIALS AND METHODS

This retrospective study included 164 patients from January 2012 to June 2019. Biochemical parameters, serial immunoglobulin G anti-ABO titers, and class I and II donor-specific antibody findings were obtained from hospital records, and renal graft biopsies were reviewed according to the Banff 2017 update.

RESULTS

We analyzed the results of 65 biopsies from 54 patients. Biopsy-proven acute antibody-mediated rejection (12.8%) was found to be more prevalent than acute cellular rejection (1.8%). Patients with antibodymediated rejection all had microvascular inflammation (g+ptc score of 2 or more, where g+ptc is the sum of the glomerulitis and peritubular capillaritis scores) and were positive for C4d. Acute tubular injury per se was seen in 10.3% of patients; 65% of these patients had C4d positivity in peritubular capillaries, and only 1 patient developed chronic active antibody-mediated rejection on follow-up. Patient and death-censored graft survival rates were 92% and 98% at 1 year after transplant and 88% and 91% at 3 years, respectively. Patients with an episode of antibody-mediated rejection had lower rates of patient (76.5%) and deathcensored graft survival (84.6%) at 1 year.

CONCLUSIONS

The microvascular inflammation score (g+ptc score of 2 or higher) is more reliable than diffuse C4d positivity to determine antibody-mediated rejection in ABO-incompatible transplants because diffuse C4d positivity may also be seen in etiologies unrelated to antibody-mediated rejection. Acute tubular injury with C4d positivity without microvascular injury does not confirm antibody-mediated rejection. We suggest that Banff classification be updated in ABOincompatible transplants to include diagnostic criteria for the diagnosis of antibody-mediated rejection.

Impact of Graft Weight Change During Perfusion on Hepatocellular Carcinoma Recurrence After Living Donor Liver Transplantation

BACKGROUNDS

Inadequate liver volume and weight is a major source of morbidity and mortality after adult living donor liver transplantation (LDLT). The purpose of our study was to investigate HCC recurrence, graft failure, and patient survival according to change in right liver graft weight after histidine-tryptophan-ketoglutarate (HTK) solution perfusion in LDLT.

METHODS

Two hundred twenty-eight patients underwent LDLT between 2013 and 2017. We calculated the change in graft weight by subtracting pre-perfusion graft weight from post-perfusion graft weight. Patients with increased graft weight were defined as the positive group, and patients with decreased graft weight were defined as the negative group.

RESULTS

After excluding patients who did not meet study criteria, 148 patients underwent right or extended right hepatectomy. The negative group included 89 patients (60.1%), and the positive group included 59 patients (39.9%). Median graft weight change was -28 g (range; -132-0 g) in the negative group and 21 g (range; 1-63 g) in the positive group (P<0.001). Median hospitalization time was longer for the positive group than the negative group (27 days vs. 23 days; P=0.048). There were no statistical differences in tumor characteristics, postoperative complications, early allograft dysfunction, or acute rejection between the two groups. Disease-free survival, death-censored graft survival, and patient survival were lower in the positive group than the negative group. Additionally, the positive group showed strong association with HCC recurrence, death-censored graft survival, and patient survival in multivariate analysis.

CONCLUSION

This study suggests that positive graft weight change during HTK solution perfusion indicates poor prognosis in LDLT.

Histidine in Health and Disease: Metabolism, Physiological Importance, and Use as a Supplement

L-histidine (HIS) is an essential amino acid with unique roles in proton buffering, metal ion chelation, scavenging of reactive oxygen and nitrogen species, erythropoiesis, and the histaminergic system. Several HIS-rich proteins (e.g., haemoproteins, HIS-rich glycoproteins, histatins, HIS-rich calcium-binding protein, and filaggrin), HIS-containing dipeptides (particularly carnosine), and methyl- and sulphur-containing derivatives of HIS (3-methylhistidine, 1-methylhistidine, and ergothioneine) have specific functions. The unique chemical properties and physiological functions are the basis of the theoretical rationale to suggest HIS supplementation in a wide range of conditions. Several decades of experience have confirmed the effectiveness of HIS as a component of solutions used for organ preservation and myocardial protection in cardiac surgery. Further studies are needed to elucidate the effects of HIS supplementation on neurological disorders, atopic dermatitis, metabolic syndrome, diabetes, uraemic anaemia, ulcers, inflammatory bowel diseases, malignancies, and muscle performance during strenuous exercise. Signs of toxicity, mutagenic activity, and allergic reactions or peptic ulcers have not been reported, although HIS is a histamine precursor. Of concern should be findings of hepatic enlargement and increases in ammonia and glutamine and of decrease in branched-chain amino acids (valine, leucine, and isoleucine) in blood plasma indicating that HIS supplementation is inappropriate in patients with liver disease.