Assessment of Connexin43 Hemichannel Functionality Based on Cytosolic Uptake of Yo-Pro1

Connexin proteins are the building blocks of gap junctions and connexin hemichannels. Both provide a pathway for cellular communication. Gap junctions support intercellular communication mechanisms and regulate homeostasis. In contrast, open connexin hemichannels connect the intracellular compartment and the extracellular environment, and their activation fuels inflammation and cell death. The development of clinically applicable connexin hemichannel blockers for therapeutic purposes is therefore gaining momentum. This chapter describes a well-established protocol optimized for assessing connexin hemichannel activity by using the reporter dye Yo-Pro1.

Nanobody-based pannexin1 channel inhibitors reduce inflammation in acute liver injury

BACKGROUND

The opening of pannexin1 channels is considered as a key event in inflammation. Pannexin1 channel-mediated release of adenosine triphosphate triggers inflammasome signaling and activation of immune cells. By doing so, pannexin1 channels play an important role in several inflammatory diseases. Although pannexin1 channel inhibition could represent a novel clinical strategy for treatment of inflammatory disorders, therapeutic pannexin1 channel targeting is impeded by the lack of specific, potent and/or in vivo-applicable inhibitors. The goal of this study is to generate nanobody-based inhibitors of pannexin1 channels.

RESULTS

Pannexin1-targeting nanobodies were developed as potential new pannexin1 channel inhibitors. We identified 3 cross-reactive nanobodies that showed affinity for both murine and human pannexin1 proteins. Flow cytometry experiments revealed binding capacities in the nanomolar range. Moreover, the pannexin1-targeting nanobodies were found to block pannexin1 channel-mediated release of adenosine triphosphate. The pannexin1-targeting nanobodies were also demonstrated to display anti-inflammatory effects in vitro through reduction of interleukin 1 beta amounts. This anti-inflammatory outcome was reproduced in vivo using a human-relevant mouse model of acute liver disease relying on acetaminophen overdosing. More specifically, the pannexin1-targeting nanobodies lowered serum levels of inflammatory cytokines and diminished liver damage. These effects were linked with alteration of the expression of several NLRP3 inflammasome components.

CONCLUSIONS

This study introduced for the first time specific, potent and in vivo-applicable nanobody-based inhibitors of pannexin1 channels. As demonstrated for the case of liver disease, the pannexin1-targeting nanobodies hold great promise as anti-inflammatory agents, yet this should be further tested for extrahepatic inflammatory disorders. Moreover, the pannexin1-targeting nanobodies represent novel tools for fundamental research regarding the role of pannexin1 channels in pathological and physiological processes.

Pannexin1 channels in the liver: an open enemy

Pannexin1 proteins form communication channels at the cell plasma membrane surface, which allow the transfer of small molecules and ions between the intracellular compartment and extracellular environment. In this way, pannexin1 channels play an important role in various cellular processes and diseases. Indeed, a plethora of human pathologies is associated with the activation of pannexin1 channels. The present paper reviews and summarizes the structure, life cycle, regulation and (patho)physiological roles of pannexin1 channels, with a particular focus on the relevance of pannexin1 channels in liver diseases.

HPB P04 The DISSECT trial, ‘The effect of periaDventitIal SMA diSsECTion on margin status during pancreaticoduodenectomy for resectable pancreatic cancer’ Results of safety and feasibility pilot study

Background

Survival following pancreatic cancer resection remains poor despite advances in adjuvant and neoadjuvant therapy. The incidence of positive margin status (R1) is high and an R1 resection is associated with poorer survival. The most commonly positive margin is the SMA, accounting for between 47–77% of R1 resections. Periadventitial dissection of the SMA includes the lymphoneural tissue around the adventitia in addition to the ‘mesopancreas’ in the resection specimen and is used to varying extent across different centres. Theoretically this technique should reduce R1 resection rate, however, there is a lack of prospective evidence in the published literature.

Methods

The DISSECT trial is a single centre, randomised control trial. All patients with a resectable as per NCCN staging criteria head of pancreas tumour are randomised to either ‘periadventitial SMA dissection’ or ‘no periadventitial SMA dissection’ (1:1 block randomisation, sealed envelope system). A standardised technique for length and circumference of dissection is used and intra-operative photography with blinded assessment of dissection status ensures quality control. This safety and feasibility stage assesses recruitment, technique and complications and will be followed by a study powered to detect the primary outcome of reduction in positive SMA margin status. Primary outcomes to be assessed in the fully powered study will be the SMA margin status as detailed by the AJCC 8th edition. Secondary outcomes are status of other margins, length of stay, complications, overall and disease-free survival, complications, and adjuvant treatment details. These are assessed prospectively by an investigator blinded to the study arm.

Results

For the feasibility stage, the following criteria were set to proceed: recruitment of 20 patients in 6 months, at least 80% of recruited patients to undergo correct arm of randomisation, and an increase in complication rate of no more than 10%. Within the first 6 months, 32 patients were successfully recruited and randomised. 6 were excluded post-randomisation but before SMA approach (N=2 cancelled and not re-booked, N=2 abandoned after opening, N=2 converted to total pancreatectomy). N=3 were eligible but not recruited, (2 refused after approach and 1 was missed due to research team capacity). N=25 (96.2%) underwent their allocated study arm (confirmed by blinded photo assessment). For potentially procedure related complications (SMA bleed, post-operative haemorrhage, chyle leak, collection, and anastomotic leak) there was an overall rate of 38.5%, with no significant difference between the 2 arms (42.9% in No SMA dissection arm and 33.3% in the SMA dissection arm). There were no incidences of SMA branch bleed in the SMA dissection arm and a single post-operative haemorrhage in the SMA dissection arm that was due to a mesenteric venous bleed.

Conclusions

The DISSECT trial is a randomised controlled trial that aims to evaluate the use of a standardised technique of periadventitial SMA dissection to reduce the rate of R1 resection in early stages of pancreatic cancer. The feasibility and safety pilot is complete and demonstrates successful recruitment and randomisation, excellent adherence to randomisation arm and no operative concerns from the surgical team. The study will now proceed to full recruitment with complications and blinded photo reviews for quality control assessed contemporaneously. Primary and secondary outcomes will be recorded prospectively by a member of the research team blinded to randomisation arm.

Impact of tumor size on the difficulty of laparoscopic left lateral sectionectomies

BACKGROUND

Tumor size (TS) represents a critical parameter in the risk assessment of laparoscopic liver resections (LLR). Moreover, TS has been rarely related to the extent of liver resection. The aim of this study was to study the relationship between tumor size and difficulty of laparoscopic left lateral sectionectomy (L-LLS).

METHODS

The impact of TS cutoffs was investigated by stratifying tumor size at each 10 mm-interval. The optimal cutoffs were chosen taking into consideration the number of endpoints which show a statistically significant split around the cut-points of interest and the magnitude of relative risk after correction for multiple risk factors.

RESULTS

A total of 1910 L-LLS were included. Overall, open conversion and intraoperative blood transfusion were 3.1 and 3.3%, respectively. The major morbidity rate was 2.7% and 90-days mortality 0.6%. Three optimal TS cutoffs were identified: 40-, 70-, and 100-mm. All the selected cutoffs showed a significant discriminative power for the prediction of open conversion, operative time, blood transfusion and need of Pringle maneuver. Moreover, 70- and 100-mm cutoffs were both discriminative for estimated blood loss and major complications. A stepwise increase in rates of open conversion rate (Z = 3.90, P < .001), operative time (Z = 3.84, P < .001), blood loss (Z = 6.50, P < .001), intraoperative blood transfusion rate (Z = 5.15, P < .001), Pringle maneuver use (Z = 6.48, P < .001), major morbidity(Z = 2.17, P = .030) and 30-days readmission (Z = 1.99, P = .047) was registered as the size increased.

CONCLUSION

L-LLS for tumors of increasing size was associated with poorer intraoperative and early postoperative outcomes suggesting increasing difficulty of the procedure. We determined three optimal TS cutoffs (40-, 70- and 100-mm) to accurately stratify surgical difficulty after L-LLS.

Limited liver resections in the posterosuperior segments: international multicentre propensity score-matched and coarsened exact-matched analysis comparing the laparoscopic and robotic approaches

Background

Limited liver resections (LLRs) for tumours located in the posterosuperior segments of the liver are technically demanding procedures. This study compared outcomes of robotic (R) and laparoscopic (L) LLR for tumours located in the posterosuperior liver segments (IV, VII, and VIII).

Methods

This was an international multicentre retrospective analysis of patients who underwent R-LLR or L-LLR at 24 centres between 2010 and 2019. Patient demographics, perioperative parameters, and postoperative outcomes were analysed; 1 : 3 propensity score matching (PSM) and 1 : 1 coarsened exact matching (CEM) were performed.

Results

Of 1566 patients undergoing R-LLR and L-LLR, 983 met the study inclusion criteria. Before matching, 159 R-LLRs and 824 L-LLRs were included. After 1 : 3 PSM of 127 R-LLRs and 381 L-LLRs, comparison of perioperative outcomes showed that median blood loss (100 (i.q.r. 40–200) versus 200 (100–500) ml; P = 0.003), blood loss of at least 500 ml (9 (7.4 per cent) versus 94 (27.6 per cent); P &lt; 0.001), intraoperative blood transfusion rate (4 (3.1 per cent) versus 38 (10.0 per cent); P = 0.025), rate of conversion to open surgery (1 (0.8 per cent) versus 30 (7.9 per cent); P = 0.022), median duration of Pringle manoeuvre when applied (30 (20–46) versus 40 (25–58) min; P = 0.012), and median duration of operation (175 (130–255) versus 224 (155–300); P &lt; 0.001) were lower in the R-LLR group compared with the L-LLR group. After 1 : 1 CEM of 104 R-LLRs with 104 L-LLRs, R-LLR was similarly associated with significantly reduced blood loss and a lower rate of conversion to open surgery.

Conclusion

Based on a matched analysis of well selected patients, both robotic and laparoscopic access could be undertaken safely with good outcomes for tumours in the posterosuperior liver segments.

A scoring system for predicting malignancy in intraductal papillary mucinous neoplasms of the pancreas: a multicenter EUROPEAN validation

PURPOSE

A preoperative estimate of the risk of malignancy for intraductal papillary mucinous neoplasms (IPMN) is important. The present study carries out an external validation of the Shin score in a European multicenter cohort.

METHODS

An observational multicenter European study from 2010 to 2015. All consecutive patients undergoing surgery for IPMN at 35 hospitals with histological-confirmed IPMN were included.

RESULTS

A total of 567 patients were included. The score was significantly associated with the presence of malignancy (p < 0.001). In all, 64% of the patients with benign IPMN had a Shin score < 3 and 57% of those with a diagnosis of malignancy had a score ≥ 3. The relative risk (RR) with a Shin score of 3 was 1.37 (95% CI: 1.07-1.77), with a sensitivity of 57.1% and specificity of 64.4%.

CONCLUSION

Patients with a Shin score ≤ 1 should undergo surveillance, while patients with a score ≥ 4 should undergo surgery. Treatment of patients with Shin scores of 2 or 3 should be individualized because these scores cannot accurately predict malignancy of IPMNs. This score should not be the only criterion and should be applied in accordance with agreed clinical guidelines.

Connexin-Based Channels in the Liver

Connexin proteins oligomerize in hexameric structures called connexin hemichannels, which then dock to form gap junctions. Gap junctions direct cell-cell communication by allowing the exchange of small molecules and ions between neighboring cells. In this way, hepatic gap junctions support liver homeostasis. Besides serving as building blocks for gap junctions, connexin hemichannels provide a pathway between the intracellular and the extracellular environment. The activation of connexin hemichannels is associated with acute and chronic liver pathologies. This article discusses the role of gap junctions and connexin hemichannels in the liver. © 2022 American Physiological Society. Compr Physiol 12:1-17, 2022.

Effects of Drugs Formerly Suggested for COVID-19 Repurposing on Pannexin1 Channels

Although many efforts have been made to elucidate the pathogenesis of COVID-19, the underlying mechanisms are yet to be fully uncovered. However, it is known that a dysfunctional immune response and the accompanying uncontrollable inflammation lead to troublesome outcomes in COVID-19 patients. Pannexin1 channels are put forward as interesting drug targets for the treatment of COVID-19 due to their key role in inflammation and their link to other viral infections. In the present study, we selected a panel of drugs previously tested in clinical trials as potential candidates for the treatment of COVID-19 early on in the pandemic, including hydroxychloroquine, chloroquine, azithromycin, dexamethasone, ribavirin, remdesivir, favipiravir, lopinavir, and ritonavir. The effect of the drugs on pannexin1 channels was assessed at a functional level by means of measurement of extracellular ATP release. Immunoblot analysis and real-time quantitative reversetranscription polymerase chain reaction analysis were used to study the potential of the drugs to alter pannexin1 protein and mRNA expression levels, respectively. Favipiravir, hydroxychloroquine, lopinavir, and the combination of lopinavir with ritonavir were found to inhibit pannexin1 channel activity without affecting pannexin1 protein or mRNA levels. Thusthree new inhibitors of pannexin1 channels were identified that, though currently not being used anymore for the treatment of COVID-19 patients, could be potential drug candidates for other pannexin1-related diseases.

Effects of Drugs Formerly Proposed for COVID-19 Treatment on Connexin43 Hemichannels

Connexin43 (Cx43) hemichannels form a pathway for cellular communication between the cell and its extracellular environment. Under pathological conditions, Cx43 hemichannels release adenosine triphosphate (ATP), which triggers inflammation. Over the past two years, azithromycin, chloroquine, dexamethasone, favipiravir, hydroxychloroquine, lopinavir, remdesivir, ribavirin, and ritonavir have been proposed as drugs for the treatment of the coronavirus disease 2019 (COVID-19), which is associated with prominent systemic inflammation. The current study aimed to investigate if Cx43 hemichannels, being key players in inflammation, could be affected by these drugs which were formerly designated as COVID-19 drugs. For this purpose, Cx43-transduced cells were exposed to these drugs. The effects on Cx43 hemichannel activity were assessed by measuring extracellular ATP release, while the effects at the transcriptional and translational levels were monitored by means of real-time quantitative reverse transcriptase polymerase chain reaction analysis and immunoblot analysis, respectively. Exposure to lopinavir and ritonavir combined (4:1 ratio), as well as to remdesivir, reduced Cx43 mRNA levels. None of the tested drugs affected Cx43 protein expression.

An international multicenter propensity-score matched and coarsened-exact matched analysis comparing between robotic versus laparoscopic partial liver resections of the anterolateral segments

BACKGROUND

Robotic liver resections RLR may have the ability to address some of the drawbacks of laparoscopic(L)LR but few studies have done a head-to-head comparison of the outcomes after anterolateral segment resections by the two techniques.

METHODS

A retrospective study was conducted of 3202 patients who underwent minimally-invasive LR of the anterolateral liver segments at 26 international centres from 2005 to 2020. 2606 cases met study criteria of which there were 358 RLR and 1868 LLR. Peri-operative outcomes were compared between the two groups using a 1:3 Propensity Score Matched(PSM) and 1:1 Coarsened Exact Matched(CEM) analysis.

RESULTS

Patients matched after 1:3 PSM(261 RLR vs. 783 LLR) and 1:1 CEM(296 RLR vs. 296 LLR) revealed no significant differences in length of stay, readmission rates, morbidity, mortality and involvement of or close oncological margins. RLR surgeries were associated with significantly less blood loss(50ml vs. 100ml, p<0.001) and lower rates of open conversion on both PSM(1.5% vs. 6.8%, p=0.003) and CEM(1.4% vs. 6.4%, p=0.004) compared to LLR. Though PSM analysis showed RLR to have a longer operating time than LLR(170 min vs. 160 min, p=0.036), this difference proved to be insignificant on CEM(167 min vs. 163 min. p=0.575).

CONCLUSION

This multicentre international combined PSM and CEM study showed that both RLR and LLR have equivalent perioperative outcomes when performed in selected patients at high volume centres. The robotic approach was associated with significantly lower blood loss and allowed more surgeries to be completed in a minimally-invasive fashion.

Variations between the anatomical and functional distribution, based on 99m technetium -mebrofinate SPECT-CT scan, in patients at risk of post hepatectomy liver failure

BACKGROUND

The aim of the current study is to investigate the variations of anatomical (LV_Rem%) and functional remnant volumes (fLV_Rem%) and the dynamic uptake of Technetium-Mebrofinate (FRLF) measured from 99^m Technetium-Mebrofinate SPECT-CT scan (TMSCT) in patients at high risk of post-hepatectomy liver failure (PHLF).

METHODS

Variations in the measures of LV_Rem% and fLV_Rem% were assessed. The predictive accuracies of LV_Rem%, fLV_Rem% and FRLF with respect to PHLF were reported.

RESULTS

From the N = 92 scans performed, LV_Rem% and fLV_Rem% returned identical results in 15% of cases, and ±10 percentage points in 79% of cases. Some patients had larger discrepancies, with difference of >10 percentage points in 21% of cases. The difference was significant in those with primary liver cancers (-4.4 ± 9.2, p = 0.002). For the N = 29 patients that underwent surgery as planned on TMSCT, FRLF was a strong predictor of PHLF, with an AUROC of 0.83 (p = 0.005).

CONCLUSION

TMSCT is emerging as a useful modality in pre-operative assessment of patients undergoing major liver resection. For those with primary liver cancer, there is a significant variation in the anatomical and functional distributions that needs considered in surgical planning. Reduced FRLF, measured as the dynamic uptake in the future liver remnant, is a strong predictor of PHLF.

Human and animal fertility studies in cystinosis reveal signs of obstructive azoospermia, an altered blood-testis barrier and a subtherapeutic effect of cysteamine in testis

Cystinosis is an inherited metabolic disorder caused by autosomal recessive mutations in the CTNS gene leading to lysosomal cystine accumulation. The disease primarily affects the kidneys followed by extra-renal organ involvement later in life. Azoospermia is one of the unclarified complications which are not improved by cysteamine, which is the only available disease-modifying treatment. We aimed at unraveling the origin of azoospermia in cysteamine-treated cystinosis by confirming or excluding an obstructive factor, and investigating the effect of cysteamine on fertility in the Ctns^-/- mouse model compared with wild type. Azoospermia was present in the vast majority of infantile type cystinosis patients. While spermatogenesis was intact, an enlarged caput epididymis and reduced levels of seminal markers for obstruction neutral α-glucosidase (NAG) and extracellular matrix protein 1 (ECM1) pointed towards an epididymal obstruction. Histopathological examination in human and mouse testis revealed a disturbed blood-testis barrier characterized by an altered zonula occludens-1 (ZO-1) protein expression. Animal studies ruled out a negative effect of cysteamine on fertility, but showed that cystine accumulation in the testis is irresponsive to regular cysteamine treatment. We conclude that the azoospermia in infantile cystinosis is due to an obstruction related to epididymal dysfunction, irrespective of the severity of an evolving primary hypogonadism. Regular cysteamine treatment does not affect fertility but has subtherapeutic effects on cystine accumulation in testis.

Complete spermatogenesis in intratesticular testis tissue xenotransplants from immature non-human primate

STUDY QUESTION

Can full spermatogenesis be achieved after xenotransplantation of prepubertal primate testis tissue to the mouse, in testis or subcutaneously?

SUMMARY ANSWER

Intratesticular xenotransplantation supported the differentiation of immature germ cells from marmoset (Callithrix jacchus) into spermatids and spermatozoa at 4 and 9 months post-transplantation, while in subcutaneous transplants, spermatogenic arrest was observed at 4 months and none of the transplants survived at 9 months.

WHAT IS KNOWN ALREADY

Auto-transplantation of cryopreserved immature testis tissue (ITT) could be a potential fertility restoration strategy for patients with complete loss of germ cells due to chemo- and/or radiotherapy at a young age. Before ITT transplantation can be used for clinical application, it is a prerequisite to demonstrate the feasibility of the technique and identify the conditions required for establishing spermatogenesis in primate ITT transplants. Although xenotransplantation of ITT from several species has resulted in complete spermatogenesis, in human and marmoset, ITT has not been successful.

STUDY DESIGN, SIZE, DURATION

In this study, we used marmoset as a pre-clinical animal model. ITT was obtained from two 6-month-old co-twin marmosets. A total of 147 testis tissue pieces (~0.8-1.0 mm3 each) were transplanted into the testicular parenchyma (intratesticular; n = 40) or under the dorsal skin (ectopic; n = 107) of 4-week-old immunodeficient Swiss Nu/Nu mice (n = 20). Each mouse received one single marmoset testis tissue piece in each testis and 4-6 pieces subcutaneously. Xenotransplants were retrieved at 4 and 9 months post-transplantation and evaluations were performed with regards to transplant survival, spermatogonial quantity and germ cell differentiation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Transplant survival was histologically evaluated by haematoxylin-periodic acid Schiff (H/PAS) staining. Spermatogonia were identified by MAGE-A4 via immunohistochemistry. Germ cell differentiation was assessed by morphological identification of different germ cell types on H/PAS stained sections. Meiotically active germ cells were identified by BOLL expression. CREM immunohistochemistry was performed to confirm the presence of post-meiotic germ cells and ACROSIN was used to determine the presence of round, elongating and elongated spermatids.

MAIN RESULTS AND THE ROLE OF CHANCE

Four months post-transplantation, 50% of the intratesticular transplants and 21% of the ectopic transplants were recovered (P = 0.019). The number of spermatogonia per tubule did not show any variation. In 33% of the recovered intratesticular transplants, complete spermatogenesis was established. Overall, 78% of the intratesticular transplants showed post-meiotic differentiation (round spermatids, elongating/elongated spermatids and spermatozoa). However, during the same period, spermatocytes (early meiotic germ cells) were the most advanced germ cell type present in the ectopic transplants. Nine months post-transplantation, 50% of the intratesticular transplants survived, whilst none of the ectopic transplants was recovered (P < 0.0001). Transplants contained more spermatogonia per tubule (P = 0.018) than at 4 months. Complete spermatogenesis was observed in all recovered transplants (100%), indicating a progressive spermatogenic development in intratesticular transplants between the two time-points. Nine months post-transplantation, transplants contained more seminiferous tubules with post-meiotic germ cells (37 vs. 5%; P < 0.001) and fewer tubules without germ cells (2 vs. 8%; P = 0.014) compared to 4 months post-transplantation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Although xenotransplantation of marmoset ITT was successful, it does not fully reflect all aspects of a future clinical setting. Furthermore, due to ethical restrictions, we were not able to prove the functionality of the spermatozoa produced in the marmoset transplants.

WIDER IMPLICATIONS OF THE FINDINGS

In this pre-clinical study, we demonstrated that testicular parenchyma provides the required microenvironment for germ cell differentiation and long-term survival of immature marmoset testis tissue, likely due to the favourable temperature regulation, growth factors and hormonal support. These results encourage the design of new experiments on human ITT xenotransplantation and show that intratesticular transplantation is likely to be superior to ectopic transplantation for fertility restoration following gonadotoxic treatment in childhood.

STUDY FUNDING/COMPETING INTEREST(S)

This project was funded by the ITN Marie Curie Programme 'Growsperm' (EU-FP7-PEOPLE-2013-ITN 603568) and the scientific Fund Willy Gepts from the UZ Brussel (ADSI677). D.V.S. is a post-doctoral fellow of the Fonds Wetenschappelijk Onderzoek (FWO; 12M2815N). No conflict of interest is declared.

Testicular tissue cryopreservation is the preferred method to preserve spermatogonial stem cells prior to transplantation

RESEARCH QUESTION

Which cryopreservation method better protects reproductive potential: the cryopreservation of a testicular cell suspension (TCS) or the cryopreservation of testicular tissue (TET)?

DESIGN

Two cryopreservation strategies for spermatogonial stem cells (SSCs) were compared in a mouse model: cryopreservation as TET or as TCS. Evaluated outcomes were number of viable cells after thawing, number and length of donor-derived colonies after spermatogonial stem cell transplantation (SSCT), number of litters, litter size and number of donor-derived pups after mating.

RESULTS

Compared with cryopreserving TCS, cryopreservation of TET resulted in significantly higher numbers of viable cells after thawing (TET: 13.4  ×  10⁴ ± 7.2  ×  10⁴ versus TCS: 8.2  ×  10⁴ ± 2.7  ×  10⁴; P = 0.0002), more (TET: 47.6 ± 19.2 versus TCS: 18.5 ± 13.0; P = 0.0039) and longer (TET: 5.2 ± 1.0 mm versus TCS: 2.7 ± 1.5 mm; P = 0.0016) donor-derived colonies, and more donor-derived pups per litter (TET: 2.2 ± 0.2 versus TCS: 0.5 ± 0.1; P = 0.0008).

CONCLUSIONS

Cryopreservation of TET is the preferred method to cryopreserve SSCs prior to SSCT in a mouse model.

Does co-transplantation of mesenchymal and spermatogonial stem cells improve reproductive efficiency and safety in mice?

Background

Spermatogonial stem cell transplantation (SSCT) is a promising therapy in restoring the fertility of childhood cancer survivors. However, the low efficiency of SSCT is a significant concern. SSCT could be improved by co-transplanting transforming growth factor beta 1 (TGFβ1)-induced mesenchymal stem cells (MSCs). In this study, we investigated the reproductive efficiency and safety of co-transplanting spermatogonial stem cells (SSCs) and TGFβ1-induced MSCs.

Methods

A mouse model for long-term infertility was used to transplant SSCs (SSCT, n = 10) and a combination of SSCs and TGFβ1-treated MSCs (MSi-SSCT, n = 10). Both transplanted groups and a fertile control group (n = 7) were allowed to mate naturally to check the reproductive efficiency after transplantation. Furthermore, the testes from transplanted males and donor-derived male offspring were analyzed for the epigenetic markers DNA methyltransferase 3A (DNMT3A) and histone 4 lysine 5 acetylation (H4K5ac).

Results

The overall tubular fertility index (TFI) after SSCT (76 ± 12) was similar to that after MSi-SSCT (73 ± 14). However, the donor-derived TFI after MSi-SSCT (26 ± 14) was higher compared to the one after SSCT (9 ± 5; P = 0.002), even after injecting half of the number of SSCs in MSi-SSCT. The litter sizes after SSCT (3.7 ± 3.7) and MSi-SSCT (3.7 ± 3.6) were similar but differed significantly with the control group (7.6 ± 1.0; P < 0.001). The number of GFP⁺ offspring per litter obtained after SSCT (1.6 ± 0.5) and MSi-SSCT (2.0 ± 1.0) was also similar. The expression of DNMT3A and H4K5ac in germ cells of transplanted males was found to be significantly reduced compared to the control group. However, in donor-derived offspring, DNMT3A and H4K5ac followed the normal pattern.

Conclusion

Co-transplanting SSCs and TGFβ1-treated MSCs results in reproductive efficiency as good as SSCT, even after transplanting half the number of SSCs. Although transplanted males showed lower expression of DNMT3A and H4K5ac in donor-derived germ cells, the expression was restored to normal levels in germ cells of donor-derived offspring. This procedure could become an efficient method to restore fertility in a clinical setup, but more studies are needed to ensure safety in the long term.

Population pharmacokinetics of primaquine and the effect of hepatic and renal dysfunction: An exploratory approach

OBJECTIVES

We attempted to develop a population pharmacokinetic model for primaquine (PQ) and evaluate the effect of renal and hepatic dysfunction on PQ pharmacokinetics.

MATERIALS AND METHODS

The data were collected from a prospective, nonrandomized clinical study in healthy volunteers and patients with mild-moderate hepatic dysfunction and renal dysfunction. Model development was conducted using NONMEM^® software, and parameter estimation was conducted using first-order conditional estimation with interaction method.

RESULTS

Final data included a total of 53 study participants (13 healthy individuals, 12 with mild hepatic dysfunction, 6 with moderate hepatic dysfunction, and 22 with renal dysfunction) with 458 concentrations records. Absorption rate constant (Ka) was constrained to be higher than elimination rate constant to avoid flip-flop situation. Mild hepatic dysfunction was a significant covariate on volume of distribution, and it is approximately three folds higher compared to other subjects. Fixed effects parameter estimates of the final model - absorption rate constant (Ka), volume of distribution (V), and clearance (CL) - were 0.95/h, 498 L, and 39 L/h, respectively. Between-subject variability estimates (% CV) on Ka, V, and CL were 77, 66, and 65, respectively. Residual error was modeled as combination error model with the parameter estimates for proportion error 12% CV and additive error (standard deviation) 1.5 ng/ml.

CONCLUSION

Population pharmacokinetic modeling showed that the volume of distribution of PQ in subjects with moderate hepatic dysfunction increases approximately three folds resulting in a significantly lower plasma concentration.

What is the best protocol to cryopreserve immature mouse testicular cell suspensions?

RESEARCH QUESTION

From a clinical perspective, which parameters grant optimal cryopreservation of mouse testicular cell suspensions?

DESIGN

We studied the effect of different cryopreservation rates, the addition of sugars, different vessels and the addition of an apoptotic inhibitor on the efficiency of testicular cell suspension cryopreservation. After thawing and warming, testicular cell suspensions were transplanted to recipient mice for further functional assay. After selecting the optimal cryopreservation procedure, a second experiment compared the transplantation efficiency between the selected freezing protocol and fresh testicular cell suspensions.

RESULTS

Multiple- and single-step freezing did not differ significantly in terms of recovered viable cells (RVC) (33 ± 28% and 38 ± 25%). The addition of sucrose did not result in a higher RVC (33 ± 20%). Cells frozen in vials recovered better than those frozen in straws (52 ± 20% versus 33 ± 20%; P = 0.0049). The inclusion of an apoptosis inhibitor (z-VAD[Oe]-FMK) significantly increased the RVC after thawing (61 ± 18% versus 50 ± 17%; P = 0.0480). When comparing the optimal cryopreservation procedure with fresh testicular cell suspensions, a lower RVC (63 ± 11% versus 92 ± 4%; P < 0.0001) and number of donor-derived spermatogonial stem cell colonies per testis (34.04 ± 2.34 versus 16.78 ± 7.76; P = 0.0051) were observed.

CONCLUSION

Upon freeze-thawing or vitrification-warming, and assessment of donor-derived spermatogenesis after transplantation, Dulbecco's modified Eagle's medium supplemented with 1.5M dimethyl-sulphoxide, 10% fetal calf serum and 60 µM of Z-VAD-(OMe)-FMK in vials at a freezing rate of -1°C/min was optimal.

Can mesenchymal stem cells improve spermatogonial stem cell transplantation efficiency?

Improved treatments have led to an increased survival rate in cancer patients. However, in pre-pubertal boys, these gonadotoxic treatments can result in the depletion of the spermatogonial stem cell (SSC) pool causing lifelong infertility. SSC transplantation has been proposed as a promising technique to preserve the fertility of these patients. In mice, this technique has resulted in live-born offspring, but the efficiency of colonization remained low. This could be because of a deficient microenvironment, leading to apoptosis of the transplanted SSCs. Interestingly, mesenchymal stem cells (MSCs), being multipotent and easy to isolate and multiply in vitro, are nowadays successfully and widely used in regenerative medicine. Here, we shortly review the current understanding of MSC and SSC biology, and we hypothesize that a combined MSC-SSC transplantation might improve the efficiency of SSC colonization and differentiation as paracrine factors from MSCs may contribute to the SSC niche.

Genetic determinants of lipid-lowering response to atorvastatin therapy in an Indian population

WHAT IS KNOWN AND OBJECTIVE

Statins form the backbone of lipid-lowering therapy for the prevention of cardiovascular disease. However, there is large interindividual variability in clinical response to statin treatment. Several gene variants that can be aligned to either the pharmacokinetics or pharmacodynamics of statin have been proposed as potentially important determinants of statin response. We aimed to study the association of known variations in SLCO1B1, CYP3A4, ABCB1, CYP3A5, ABCG5 and CYP7A1 genes with lipid levels in response to atorvastatin therapy.

METHODS

Genotypes were determined using multiplex allele-specific polymerase chain reaction in 177 Indian patients, treated with 10 mg of atorvastatin for 8 weeks. Low-density lipoprotein-cholesterol (LDL-C) levels were recorded at baseline and after 8 weeks of atorvastatin treatment.

RESULTS AND DISCUSSION

A total of 177 hypercholesterolaemic patients were genotyped to study genetic determinants of atorvastatin response. The genotype distribution for all polymorphisms investigated was in Hardy-Weinberg equilibrium. In our study, patients with wild-type genotypes of CYP7A1 (rs3808607), CYP3A4 (rs2740574), SLCO1B1 (rs2306283) and variant allele-carrying genotype of ABCB1 (rs2032582, rs1045642) showed significantly greater LDL-cholesterol reductions in response to atorvastatin therapy.

WHAT IS NEW AND CONCLUSION

The variable response to atorvastatin therapy in terms of LDL-cholesterol lowering due to genetic variations in CYP7A1, CYP3A4, SLCO1B1 and ABCB1 is a promising finding. Further validation in large Indian cohorts is required before it can be assessed for clinical utility.

Excision of carbuncle with primary split-thickness skin grafting as a new treatment modality

Carbuncles are debilitating skin infections commonly seen in diabetic patients. Excision of these infective lesions leads to large defects that require prolonged hospital stay and repeated dressings with ensuing pain and bleeding. This study is an attempt to cover the wounds resulting from excision of carbuncle with primary skin grafting so as to decrease the hospital stay and frequency of dressings.

A study of mast cells in granulomatous lesions of skin, with special emphasis on leprosy

76 skin biopsies that included material from 7 controls, 65 granulomatous skin lesions and 2 each of granulation tissue and chronic non-specific inflammation, were subjected to histopathological evaluation on haematoxylin and eosin and pertinent special stains. Mast cell study was done on slides stained by toluidine blue method, with special reference to their location, and morphology and cell count were done with the help of occculomicrometre. In normal skin, mast cell density was 11.43/mm2 with a range of 6-22/mm2 and an S.D. of 5.94. Highest value in the whole series was seen in TVC (66/mm2), followed by lupus vulgaris (50/mm2). Mast cell counts were normal in indeterminate and TT leprosy and showed a rise over the immunological spectrum BT to LL, with values in LL being 32.86/mm2 (28-40/mm2).

Acute promyelocytic leukemia: all-trans retinoic acid (ATRA) along with chemotherapy is superior to ATRA alone

This study was conducted to compare the results of treatment of acute promyelocytic leukemia (APL) with all-trans retinoic acid alone (ATRA) or a combination therapy of ATRA followed by chemotherapy. Forty-three patients treated between February 1992 and February 1996 were included in this study. Eighteen patients were treated with ATRA alone and 25 patients were treated with ATRA followed by chemotherapy. The cytogenetic analysis was done in 41 patients at presentation, following treatment, and at follow-up. A complete response (CR) was achieved in 13 (72%) patients on ATRA and 19 (76%) on ATRA followed by chemotherapy. Eleven of 13 patients with response to ATRA alone relapsed with median survival of eight months (range, 1 to 28). One patient died of hepatitis in CR and one patient is alive 2 years after diagnosis. In the combination therapy arm, 10 patients are in CR with a median follow-up of 22 months (range, 6 to 56 months). After achieving a CR, four patients died due to infections during chemotherapy therapy, and only 5 of 19 patients have relapsed. Major cytogenetic response was seen in 8 of the 10 patients in whom cytogenetic data was available after treatment with ATRA at the time of remission. Similarly, 13 of 15 for whom data was available showed a major cytogenetic response after treatment with ATRA plus chemotherapy. Prior to relapse, 80% of the patients had an increase in the percentage of t(15;17) cells in the marrow. Patients with a complete hematological response but no cytogenetic response relapsed within six months. Ten patients died prior to response evaluation. Two patients who received ATRA died of retinoic acid syndrome, one of pneumonia, and one of intracranial hemorrhage. Of the six patients on ATRA and chemotherapy, four died of retinoic acid syndrome (RAS), one of intracranial hemorrhage, and one of left ventricular failure. Only one patient is alive at 24 months following treatment with ATRA alone. The relapse-free survival is 42% at four years for patients treated with ATRA followed by chemotherapy. This trial is a historical comparison of ATRA alone and ATRA with subsequent combination chemotherapy. Nonetheless, the trial shows a significant improvement in the event free survival of patients receiving chemotherapy as consolidation following ATRA.

All-trans-retinoic acid (ATRA): pediatric acute promyelocytic leukemia

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloblastic leukemia (AML). In this report, we present the clinical features, management, and outcome of pediatric patients with APL treated with all-trans-retinoic acid (ATRA). Of 52 newly diagnosed cases of APL between February 1992 and December 1996, 15 were in the pediatric age group (younger than 15 years). Four patients were treated with ATRA alone and 11 were allocated to receive ATRA followed by chemotherapy. Eighty-six percent of the patients achieved a complete response. The patients who received ATRA alone as maintenance therapy had relapses with a median duration of remission of 8 months (range 6-12). The patients who received ATRA, followed by consolidation chemotherapy, had a prolonged duration of remission, with a median of 20 months (range 13-28). In addition, rapid correction of coagulopathy was observed in these patients. The median duration for correction of coagulopathy was 7 days (range 5-11) and the median duration for recovery from neutropenia after chemotherapy was 10 days (range 7-20). Two major side effects of ATRA were hyperleukocytosis and retinoic acid syndrome. Significantly prolonged disease-free survival was seen in patients who received ATRA with chemotherapy. APL is not uncommon in the pediatric age group. ATRA was well-tolerated by these patients. Consolidation with chemotherapy helps in prolonging the disease-free survival in patients with APL in comparison to treatment with ATRA alone.

Chromosome investigations & clinical outcome in patients with myelodysplastic syndromes

A total of 25 patients with primary myelodysplastic syndrome (p-MDS) were cytogenetically investigated. The incidence of abnormal karyotypes was higher, detected in 88 per cent of the patients and the most frequent abnormality was a terminal deletion of chromosome 7 (45% of the patients with abnormal karyotypes) followed by an i (17q) (18%), +21(14%), -5/5q (9%), del (11) (q22) (9%). Cytogenetic analysis after therapy/after leukaemic transformation indicated either stable clones (2 patients) or emergence of new clones such as inv(5) (q32q36), del (17) (p13), +20, +22 (1 patient each). It is to be noted that of the 8 patients with leukaemic transformation, 5 had del (7q). The leukaemic transformation (32% of the patients) was not related to the percentage of abnormal karyotypes not to the percentage of blasts at the time of the MDS presentation. Chromosome instability was shown by 10 (45%) patients. Our data indicate that higher frequency of chromosomal aberrations with involvement of chromosome 7 may be the result of underlying disease.

Detection of unexpected clones of monosomy 7 in childhood acute lymphoblastic leukemia using fluorescence in situ hybridization

The feasibility of a fluorescence in situ hybridization (FISH) technique for the detection of leukemic clones with masked chromosomal aberration in interphase nuclei was tested in childhood acute lymphoblastic leukemia (ALL). Twenty-one cases of ALL previously studied by classical metaphase cytogenetics were retrospectively analysed using a centromere-specific chromosome 7 probe. Five cases with karyotypic abnormalities of chromosome 7 (2 with trisomy 7, 2 with monosomy 7 and 1 with trisomy & tetrasomy 7) showed a correlation with FISH results, whereas in five other cases monosomy 7 was found in 12-43% of cells only by FISH. The unexpected detection of monosomy 7 in these latter ALL patients suggests that either these clones are quiescent or unable to enter mitosis in vitro. This suggests that FISH and metaphase cytogenetics must be combined whenever possible to obtain comprehensive karyotypic information.

Inhibition of progesterone action by a factor in human follicular fluid

A factor was found in human follicular fluid that blocked progesterone-stimulated net uptake of 45Ca2+ in human sperm and progesterone-induced maturation of Xenopus oocyte. The factor was partially purified by ultrafiltration through PM-10 membrane and gel filtration on Sephadex G-25 column. The active fraction is effective at a concentration of 200 micrograms/ml. The present findings suggest that hFF factor may regulate the metabolism of progesterone sensitive cells.

Analysis of the c-myc and N-ras genes in acute myelogenous leukemia cells which manifest the constitutive expression of the c-myc gene

The "constitutive" expression of the c-myc gene was detected in leukemia cells obtained from 4 patients with an acute myeloid leukemia, 3 with chronic myeloid leukemia and 1 with a myelodysplastic syndrome. Studies were undertaken to determine whether or not the myc gene was rearranged or mutated in exon I within a 3'Pvu II region, a transcriptional attenuation site. Studies to explore the possibility of a point mutation in the N-ras gene were also conducted. No abnormalities were detected in either gene. Studies should be undertaken evaluating the possibility of a post-transcriptional mechanism, such as alteration of RNA stability, which could be responsible for the constitutive expression of c-myc gene.

Combination of classical and interphase cytogenetics to investigate the biology of myeloid disorders: detection of masked monosomy 7 in AML

Numerical abnormalities of chromosome 7 were detected by using fluorescence labeled in situ hybridization (FISH) procedure with a centromere-specific probe in four cases of acute myeloid leukemia (AML) and three cases of myelodysplastic syndromes (MDS). Comparison of these results with classical cytogenetic (CC) data demonstrated a good correlation between the two methods. FISH confirmed the finding of monosomy 7 in all patients who demonstrated this abnormality by CC. Two AML patients who did not show monosomy 7 by CC were unexpectedly found to contain this abnormality in 39.8% and 17% cells when examined by FISH. Given that our modified FISH method consistently yielded > 96% hybridization efficiency, these findings constitute an unexpected but real presence of monosomy 7 in a substantial number of interphase cells that had remained undetected by classical karyotyping. Finally, a number of maturing myeloid cells including granulocytes also demonstrated monosomy 7 by FISH, thereby confirming the ability of malignant cells to undergo differentiation. We conclude that FISH constitutes a highly sophisticated molecular technique which can be extremely useful in select cases for detecting 'masked monosomy 7' as well as helping to determine the lineage of terminally mature cells in AML, thereby providing a handle on the effects of cytokines or chemotherapy on normal vs leukemic clones.

Abnormal regulation of the myc gene in myeloid leukemia

To study the regulation of expression of the myc protooncogene, cells from normal individuals and patients with acute myelogenous leukemia (AML), and chronic phase and blastic crisis of chronic myeloid leukemia (CML) cells were put in overnight culture in the presence or absence of fetal calf serum. Myc expression in normal marrow cells and chronic phase CML cells fell after culture in vitro. In contrast, myc expression was maintained or increased in a majority of the AML and blastic crisis CML specimens. These data demonstrate that the regulation of myc expression is disordered in many AML and blastic crisis specimens but not in chronic phase CML cells.

The multiple drug resistance gene, MDR1: expression at the protein and RNA levels

A comparison of three different approaches to detect MDR1 expression in myeloid leukemia cells was undertaken. With respect to the 4 different antibodies studied, a high proportion of false positive reactions were detected. Substantial discordance between MDR1 expression as indicated by Northern blot analysis, PCR, and immunohistochemistry was found. These findings complicate the clinical interpretation of data derived from these methods.

Chronic myelomonocytic leukaemia (an analysis of fourteen consecutive cases)

Fourteen consecutive cases of chronic myelomonocytic leukaemia aged 6 to 73 (mean 40.5) years were reviewed to define the natural history of the disease and the risk of acute transformation. The common presenting features included anaemia, fever, purpura, and bleeding tendencies. Abnormal karyotypes were seen in 4 of 6 patients subjected to cytogenetic analysis. Low dose cytosine arabinoside achieved complete remission in two and partial remission in one, of the four patients treated with this modality. The mean survival was 5.6 (range 2-12) months and two patients) evolved to acute myeloid leukaemia. The long term survival with the present form of therapy in chronic myelomonocytic leukaemia is poor.

Isolation and partial characterisation of human riboflavin carrier protein and the estimation of its levels during human pregnancy

Human cord serum contains protein(s) capable of binding to [14C]-riboflavin. Riboflavin-bound protein cross-reacts with anti-serum to chicken riboflavin carrier protein (cRCP). The carrier protein was isolated using affinity chromatography on a riboflavin AH Sepharose column. Bulk isolation and purification was also attempted by a combination of ion exchange, gel filtration and gel permeation chromatography on HPLC. The protein so isolated had a molecular weight of 36,000 +/- 2,000 daltons with an isoelectric point of 4.1. The levels of RCP in maternal serum during pregnancy were monitored using a sensitive heterologous radioimmunoassay system, using cRCP as standard and anti serum to cRCP. The levels of the protein increased after 4 months and remained significantly elevated up to 8 months. Although the level of the protein in the maternal serum remained low until 4 months, its level in amniotic fluid was elevated 2-3-fold as compared to that in serum.

Do heart valve bioprostheses degenerate for metabolic or mechanical reasons?

Although heart valve bioprostheses provide a normal quality of life, their durability is still of great concern. Their durability failure is defined as "degeneration," which is considered to be a consequence of metabolic factors. In this study, we demonstrate that mechanical and design factors can also be responsible for bioprosthesis failure. Large numbers of porcine and pericardial bioprostheses were tested in a fatigue-testing system in which the test conditions were proved to be reproducible and accurate by a laser Doppler anemometer. The results have allowed us to define causes of failure, previously insufficiently stressed, in each type of valve tested. There is a clear difference in factors influencing tissue disruption between porcine and pericardial valves. We have compared these in vitro results with in vivo clinical findings. The main inferences are as follows: (1) Bioprostheses rupture and fail in the same fashion in both in vitro and in vivo studies. (2) Mechanical and design factors are involved in tissue failure. (3) The in vitro/in vivo durability ratio is not 1:1. This ratio depends on the test conditions. (4) Pericardial valves fail because of damage during closure, whereas porcine valves are damaged during both opening and closing (mostly opening) because of design features. (5) Once one cusp fails and prolapses, the other cusps will fail in an accelerated fashion. (6) In vitro durability of 100 X 10(6) cycles can be considered excellent and is an achievable goal. (7) Variability is the key impediment to predicting the durability of bioprostheses. Valves can fail within 2 to 3 million cycles or can last more than 100 million cycles. Similarly, bioprostheses may require explantation within a few months or can last 10 to 13 years in patients. (8) Fatigue testing is an excellent and valuable tool to elucidate the mechanical factors responsible for this variability.

Termination of pregnancy in mice with antiserum to chicken riboflavin-carrier protein

The importance of riboflavin-carrier protein (RCP) in the maintenance of pregnancy in mice has been studied. Selective passive immunoneutralization of the maternal RCP resulted in fetal death and resorption. Six hours after chicken RCP antiserum treatment, the following observations were made: there was profuse vaginal bleeding in all the animals, a 60% reduction in embryonic ornithine decarboxylase (ODC) activity, a 70% reduction in the maternal progesterone levels, and a 50% reduction in the 14C-riboflavin uptake by the embryo. The above observations are indicative of fetal distress and resorption. By 24 h after treatment, there was 100% resorption of fetuses and the mouse progesterone levels dropped to 20% of untreated or normal rabbit serum (NRS)-treated values. Cytological studies of the fetal liver revealed the classical signs of cellular degeneration in hepatocytes as well as hematopoietic cells. The effect was apparent as early as 1 h after antiserum administration. The erythroid aplasia supports the biochemical evidence that fetal demise is due to preferential riboflavin deficiency of the fetus.