Hypothermic Liver Machine Perfusion With EKPS-1 Solution vs Aqix RS-I Solution: In Vivo Feasibility Study in a Pig Transplantation Model

OBJECTIVE

Hypothermic machine perfusion (HMP) is superior to simple cold storage for kidney preservation. We previous observed in a porcine liver transplantation model increased tumor necrosis factor-alpha (TNF-alpha) production eventually leading to poor recipient survival after HMP using standard kidney perfusion solution (KPS-1) compared with simple cold storage. We compared two solutions for HMP preservation of the liver: enriched KPS-1 (EKPS-1) and Aqix RS-I.

METHODS

Pig livers were obtained after cold flushing with histidine-tryptophan-ketoglutarate solution. Subsequently, the livers were subjected to dual-vessel perfusion with two preservation solutions: EKPS-1 (n = 6) and Aqix RS-I (n = 3). After HMP preservation and transplantation, graft and recipient survival, hepatocellular damage (aspartate aminotransferase concentration), TNF-alpha production, and endothelial cell damage (hyaluronic acid clearance) were recorded.

RESULTS

No primary graft nonfunction was observed. Recipient survival at postoperative day 3 was similar in both groups (33%). Aspartate aminotransferase concentration measured in serum samples after reperfusion was similar in both groups. After reperfusion, TNF-alpha concentration was higher and hyaluronic acid clearance was lower in the EKPS-1 group vs the Aqix RS-I group at 60, 120, and 180 minutes (all P < .05).

CONCLUSION

Hypothermic machine perfusion provided adequate longer term graft survival. After reperfusion, TNF-alpha production seems to be reduced, and endothelial cell dysfunction remains pronounced with Aqix RS-1 solution compared with EKPS-1 solution.

LUNG INFLATION WITH DIRECT INJECTION OF AGAROSE: A TECHNIQUE FOR SIMULTANEOUS MOLECULAR AND MORPHOMETRIC MEASUREMENTS

The usual methods for preparing lungs for morphologic study involve the instillation of fixatives that modifyproteins and RNA such that the tissue is unsuitable for molecular studies. To develop a technique suitable for molecular studies, pieces of adult rat lungs were infiltrated with agarose, glutaraldehyde, or paraformaldehyde and the consistency of alveolar inflation was compared to lungs inflated with 10% formalin. Only direct injection with 1% agarose resulted in comparable inflation of lung tissue and preserved RNA and protein. Thus, this technique enables simultaneous molecular and morphometric analysis of the lung on small pieces of lung tissue in heterogeneous lung diseases.

Effect of oxygenated perfluorocarbon on isolated islets during transportation

BACKGROUND

Previous studies demonstrated the efficacy of the two-layer method (TLM) using oxygenated perfluorochemicals (PFC) for pancreas preservation. The current study investigated the effect of oxygenated PFC on isolated islets during transportation.

MATERIALS AND METHODS

Purified rat islets were stored in an airtight conical tube for 24h in RPMI culture medium at 22 degrees C or University of Wisconsin solution (UW) at 4 degrees C, either with or without oxygenated PFC. After storage, the islets were assessed for in vitro viability by static incubation (SI), FDA/PI staining, and energy status (ATP, energy charge, and ADP/ATP ratio) and for in vivo viability by a transplantation study.

RESULTS

UW at 4 degrees C and RPMI medium at 22 degrees C maintained islet quality almost equally in both in vitro and in vivo assessments. The ATP levels and energy status in the groups with PFC were significantly lower than those without PFC. The groups with PFC showed a significantly higher ADP/ATP ratio than those without PFC. In the transplantation study, blood glucose levels and AUC in the UW+PFC group were significantly higher than those in UW group.

CONCLUSIONS

UW at 4 degrees C and RPMI medium at 22 degrees C maintained islet quality equally under the conditions for islet transportation. The addition of oxygenated PFC, while advantageous for pancreas preservation, is not useful for islet transportation.

Lung transplantation in pulmonary fibrosis: challenging early outcomes counterbalanced by surprisingly good outcomes beyond 15 years

Interstitial lung disease (ILD) has been reported to have a poor outcome following lung transplantation due to difficulties getting ill recipients to transplantation and challenging early postoperative outcomes. To assess long-term outcomes for this cohort, we performed a retrospective 18-year chart review of all ILD lung transplant recipients. ILD single (SLT) and bilateral sequential lung transplantations (BSLT) were compared with all other lung transplant patients and International Society for Heart and Lung Transplantation (ISHLT) Registry data over the same time period. Of 585 lung transplantations, 90 (15%) were ILD (53 SLT, 37 BSLT); 67 (74%) were idiopathic pulmonary fibrosis (IPF), 9 (10%) were sarcoidosis, 9 (10%) were lymphangioleiomyomatosis, and 5 (6%) had other indications. Mean age was 52 years (range, 34-69 years). Actuarial survival at 1, 5, 10, 15, and 18 years compared favorably to all other lung transplantations performed (77% vs 83%, 51% vs 50%, 42% vs 26%, 28% vs 17%, and 28% vs 8%, respectively). IPF actuarial survival at 1, 5, and 10 years appeared superior to ISHLT Registry data (76% vs 72%, 50% vs 44%, and 34% vs 20%, respectively). There was equivocal survival between SLT and BSLT at 1, 5, and 10 years (78% vs 68%, 49% vs 50%, and 29% vs 50%, respectively). Our ILD figures compared favorably to lung transplantation for other diseases and international standards, while survival from SLT was as successful as BSLT both in the short and the longer term. Consideration should be given to utilizing SLT to maximize the allocation of donor lungs and to decrease waiting list mortality associated with IPF.

Changes and effect of PACAP-38 on intestinal ischemia-reperfusion and autotransplantation

Tissue injury caused by cold preservation and reperfusion during small bowel transplantation remains an unsolved problem. Increasing evidence suggests that pituitary adenylate cyclase-activating polypeptide (PACAP) has protective effects in several ischemia-reperfusion (I/R) models. This study investigated the effect of PACAP-38 on oxidative stress in autotransplanted intestine. We established sham-operated, I/R, and autotransplanted groups in Wistar rats (n = 55). We applied ischemia for 1 (GI), 2 (GII), or 3 hours (GIII). In autotransplanted groups, we performed total orthotopic intestinal autotransplantation. Grafts were preserved in University of Wisconsin (UW) solution for 1 (GIV), 2 (GV), 3 (GVI), or 6 (GVII) hours and in PACAP-38-containing UW for 1 (GVIII), 2 (GIX), 3 (GX), or 6 (GXI) hours. Reperfusion lasted 3 hours in each group. Endogenous PACAP-38 values were measured by radioimmunoassay. Oxidative stress parameters malondialdehyde (MDA), reduced glutathione (GSH), and superoxide dismutase (SOD) were measured in tissue homogenates. Concentration of endogenous PACAP-38 significantly decreased in GI to GIII compared with the sham-operated animals following I/R periods (P < .05). Cold preservation in UW and reperfusion of the intestine increased the level of tissue MDA in GIV to GVII, which correlated with the duration of cold storage. The content of GSH decreased in GIV to GVII to levels that were significantly different between GIV and GVIII and between GVII and GXI. SOD activity decreased dramatically in GIV to GVII with significantly higher activity in GIX to GXI. Our findings confirmed that I/R decreased endogenous PACAP-38 concentration. Administration of PACAP-38 to UW solution mitigated the oxidative injury during intestinal autotransplantation.

Hypothermic storage of isolated human hepatocytes: a comparison between University of Wisconsin solution and a hypothermosol platform

Until now little is known about the functional integrity of human hepatocytes after hypothermic storage. In order to address this limitation, we evaluated several commercially available hypothermic preservation media for their abilities to protect freshly isolated hepatocytes during prolonged cold storage. Human hepatocytes were isolated from non-transplantable/rejected donor livers and resuspended in ice-cold University of Wisconsin solution (UW), HypoThermosol-Base (HTS-Base), or HypoThermosol-FRS (HTS-FRS) with or without the addition of fetal bovine serum. Cells were stored at 4 degrees C for 24-72 h, and evaluated for hepatocyte viability (trypan blue exclusion, or labeling with fluorochromes), cell attachment, and function. The energy status of hepatocytes was evaluated by measurement of intracellular adenosine 5'-triphosphate. To determine whether the test cells expressed metabolic functions of freshly isolated cells, the activities of major phase I (cytochromes P450, FMO) and phase II (UGT, ST) drug-metabolizing enzymes were examined. Although hepatocytes are shown to be satisfactory after 24 h storage in all of the tested solutions, the cell viability, energy status, and xenobiotic metabolism following cold preservation in HTS-FRS was consistently and, in some cases, markedly higher when compared with other systems. The same metabolites for each of the tested substrates were detected in all groups of cells. Moreover, the use of HTS-FRS eliminates the need for serum in preservation solutions. HTS-FRS represents an improved solution compared to HTS-Base and UW for extending the shipping/storage time of human hepatocytes.

Polymerized placenta hemoglobin attenuates ischemia/reperfusion injury and restores the nitroso-redox balance in isolated rat heart

Ischemia/reperfusion (I/R) injury mainly caused by oxidative stress plays a major role in cardiac damage. The extent of the I/R injury is also an important factor that determines the function of a transplanted heart. This study first examined whether hemoglobin-based oxygen carriers (HBOCs) could protect isolated rat heart from I/R injury and then elucidated the underlying mechanism. Using the Langendorff model, isolated Sprague-Dawley rat hearts were arrested and stored at 4 degrees C for 8 h and then reperfused for 2 h. Compared with St. Thomas' solution (STS) and rat self blood in STS, polymerized placenta hemoglobin (PolyPHb) in STS greatly improved heart contraction and decreased infarction size. The extent of myocardial apoptosis was also significantly decreased, which was related to reduced iNOS-derived nitric oxide production, increased protein ratio of Bcl-2/Bax, and reduced caspase-3 activity and cleavage level. Furthermore, PolyPHb in STS did not increase malondialdehyde, peroxynitrite, or mitochondrial hydrogen peroxide formation, but greatly elevated superoxide dismutase activity and preserved mitochondrial ATP synthesis, which served to maintain redox homeostasis in I/R heart. In conclusion, our results demonstrate that HBOCs protected isolated heart from I/R injury and this protection was associated with attenuation of NO-mediated myocardial apoptosis and restoration of the nitroso-redox balance.

Influence of storage media containing Salvia officinalis on survival of periodontal ligament cells

AIM

The purpose of this study was to determine the ability of Salvia officinalis (S. officinalis) extracts to serve as a storage medium for the maintenance of periodontal ligament (PDL) cell viability of avulsed teeth.

METHODS AND MATERIALS

PDL cells were obtained from healthy third molars and cultured in Dulbecco's Modi?ed Eagle's Medium (DMEM). Cultures were subjected to 4, 2.5, 1.5, and 0.5% S. officinalis solutions, Hank's balanced salt solution (HBSS), phosphate buffered saline (PBS), and tap water. Tissue culture plates were incubated with experimental media at 37 masculineC for 1, 3, 6, 12 or 24 hours. PDL cell viability was assessed by trypan blue exclusion. Statistical analysis of the data was performed by one-way analysis of variance (ANOVA) complemented by the Tukey's test. The level of significance was 5% (p< 0.05).

RESULTS

The results showed 2.5% S. officinalis was a more effective storage medium than the other experimental solutions (p<0.05). Only at 1 hour and 3 hours was there found similar effect between 2.5% S. officinalis and HBSS. At 24 hours, 2.5% S. officinalis was found to be significantly better than the other solutions tested.

CONCLUSION

S. officinalis can be recommended as a suitable transport medium for avulsed teeth.

CLINICAL SIGNIFICANCE

The findings of this study support the use of S. officinalis as another option for clinicians to use to store and transport avulsed teeth until reimplantation procedures can be done.

A new storage medium for an avulsed tooth

AIM

The purpose of this study is to determine the efficacy of egg white in maintaining the viability of human periodontal ligament (PDL) cells on avulsed teeth.

METHODS AND MATERIALS

The experimental media were: egg white, milk, Hanks' Balanced Salt Solution (HBSS) as the positive control, and tap water as the negative control. The storage times were 1, 2, 4, 8, and 12 hours. Extracted premolar teeth of healthy individuals were rinsed in the media. After trypsinization and subsequent treatment in collagenase, cell viability was determined using trypan blue staining. The two-way analysis of variance (ANOVA) statistical test was used to compare the results among different media.

RESULTS

There was no difference in the cell viability between egg white and HBSS media, but there was a statistically significant difference between the viability of PDL cells in egg white medium in comparison with milk (P<0.05) and water (P<0.05).

CONCLUSION

Egg white could be suggested as a suitable storage medium. Its principle advantage is its availability.

Pancreatic islet isolation variables in non-human primates (rhesus macaques)

BACKGROUND

Non-human primates (NHPs) are important preclinical models for pancreatic islet transplantation (PIT) because of their close phylogenetic and immunological relationship with humans. However, low availability of NHP tissue, long learning curves and prohibitive expenses constrain the consistency of isolated NHP islets for PIT studies. To advance preclinical studies, we attempted to identify key variables that consistently influence the quantity and quality of NHP islets.

METHODS

Seventy-two consecutive pancreatic islet isolations from rhesus macaques were reviewed retrospectively. A scaled down, semi-automated islet isolation method was used, and monkeys with streptozotocin-induced diabetes, weighing 3-7 kg, served as recipients for allotransplantation. We analysed the effects of 22 independent variables grouped as donor factors, surgical factors and isolation technique factors. Islet yields, success of isolation and transplantation results were used as quantitative and qualitative outcomes.

RESULTS

In the multivariate analysis, variables that significantly affected islet yield were the type of monkey, pancreas preservation, enzyme lot and volume of enzyme delivered. The variables associated with successful isolation were the enzyme lot and volume delivered. The transplant result was correlated with pancreas preservation, enzyme lot, endotoxin levels and COBE collection method.

CONCLUSIONS

Islet quantity and quality are highly variable between isolations. The data reviewed suggest that future NHP isolations should use bilayer preservation, infuse more than 80 ml of Liberase into the pancreas, collect non-fractioned tissue from the COBE, and strictly monitor for infection.

Effect of storage conditions on lactate dehydrogenase released from perfused hearts

BACKGROUND

Release of lactate dehydrogenase (LDH) is a widely used marker of tissue damage. A review of the literature indicates that after collection of coronary effluents from hearts, a variety of storage conditions have been utilized prior to measurement of LDH activity. The purpose of this study was to determine whether storage conditions reported in the literature affect LDH activity.

METHODS

Isolated rat hearts perfused with Krebs-Henseleit buffer (KHB) were subjected to 30 min of global ischemia followed by normoxic reperfusion to generate tissue damage and elevate LDH release. Coronary effluents were collected and stored at 4 degrees C, 23 degrees C, -20 degrees C, and -80 degrees C prior to measurement of LDH activity.

RESULTS

After 24 h no decline in LDH occurred at 4 degrees C storage (P>0.05), but a 42% decline occurred at 23 degrees C (P<0.05). After 48 h, activity declined (P<0.05) 11% at 4 degrees C and 98% at 23 degrees C. Frozen storage resulted in a 40% loss at -80 degrees C and a 79% loss at -20 degrees C (P<0.05).

CONCLUSIONS

Short-term storage in Krebs-Henseleit buffer for 24 h at 4 degrees C does not affect LDH activity and frozen storage should be avoided.

Cold preservation of the liver with oxygenation by a two-layer method

BACKGROUND

The two-layer method (TLM) has recently been found to be superior to simple cold storage in University of Wisconsin (UW) solution as a means of pancreas preservation for islet transplantation. In this study, we investigated whether TLM would result in better hepatocyte function over UW cold storage and if it could be applied to hepatocyte transplantation.

MATERIALS AND METHODS

Hepatocytes from male Sprague Dawley rat livers were isolated and divided into three groups: a non-preservation group (group 1), a 10-h preservation group (group 2), and a 24-h preservation group (group 3). Groups 2 and 3 were then divided into three subgroups: a group preserved by the TLM (subgroup a), a group preserved in UW solution (subgroup b), and a group preserved in water (subgroup c). Isolated hepatocytes were evaluated for cell yield, viability, and adenosine triphosphate level after preservation. Hepatocytes were either cultured or transplanted.

RESULTS

Although no differences in cell yield or morphological findings were observed between any of the groups, TLM significantly improved hepatocyte viability and adenosine triphosphate levels in comparison with UW cold storage. Albumin production or urea synthesis were significantly higher in subgroup 3a than in subgroup 3b at almost all time points. Surprisingly, after hepatocyte transplantation, the serum albumin level in subgroup 2a was significantly higher than in subgroup 2b at every time point.

CONCLUSIONS

The results of this study demonstrated that liver preservation by the TLM before hepatocyte isolation might be beneficial and will be useful in the field of hepatotocyte transplantation.

Preservation of pancreatic tissue morphology, viability and energy metabolism during extended cold storage in two-layer oxygenated University of Wisconsin/perfluorocarbon solution

BACKGROUND

In contrast to the relative scarcity of donor kidneys and hearts, the potential supply of deceased donor pancreata is exceeding the demand. However, this organ surplus is not being fully realized because, in current transplantation practice, the duration of pancreas storage before transplantation is limited to 8-10 hours due to the extreme vulnerability of pancreatic tissue to anaerobic damage caused by preservation.

OBJECTIVES

To reduce cold ischemic injury in order to increase the utilization of donor pancreases in Israel for whole-organ and cell transplantation.

METHODS

We evaluated a novel two-layer preservation oxygenated cold storage method that uses perfluorocarbon to continuously supply oxygen to the pancreas during preservation in conventional University of Wisconsin solution.

RESULTS

Pancreatic tissue morphology, viability and adenosine-triphosphate content were serially examined during preservation of the pig pancreas for 24 hours either by a two-layer or by conventional simple cold storage. Already after 12 hours of storage, the superiority of the two-layer method over the University of Wisconsin method was apparent. Starting at this time point and continuing throughout the 24 hours of preservation, the tissue architecture, mitochondrial integrity, cellular viability and ATP tissue concentration were improved in samples preserved in oxygenated UW/PFC as compared to controls stored in conventional UW solution alone.

CONCLUSIONS

The UW/PFC two-layer preservation method allowed tissue ATP synthesis and amelioration of cold ischemic tissue damage during extended 24 hour pancreas preservation. This method could be implemented in clinical practice to maximize utilization of pancreata for whole-organ and islet transplantation as well as for pancreas sharing with remote centers.

[A successful transplant begins with organ preservation]

Organ preservation is a critical link in the chain of donation and transplantation and has a significant effect on post-transplant graft function and graft survival. Clinically, the most widely used form of preservation is static cold storage, which is based on the reduction of cellular metabolism by hypothermia. Although static cold storage is simple and effective, it is questionable whether it still meets present day requirements. Due to the persistent shortage of donors, increasing numbers of organs are being accepted from older and non-heart-beating donors. Organs from such donors may benefit from a more dynamic method of preservation: hypothermic machine perfusion.

Clinica use of platelet additive solutions

Randomised clinical trial (RCT) to study the clinical efficacy and safety of new platelet products using platelet additive solutions are scarce. In this paper a number of recent RCT's is discussed. It can be the start of a development where new transfusion products enter a RCT before the product is applied in clinical practice.

Influence of flow and addition of oxygen during porcine liver hypothermic machine perfusion

INTRODUCTION

In contrast with kidneys, data on hypothermic machine perfusion (HMP) of livers remain scarce. Optimal liver HMP is poorly defined. Superiority of liver HMP over simple cold storage (SCS), the current standard preservation, must be proven before HMP is applied clinically. In this study, morphology and adenosine triphosphate (ATP) contents of HMP livers at different flows and with versus without O(2) studied in a porcine ex vivo model were compared to SCS.

METHODS

Pig livers were procured, flushed with HTK and preserved via SCS or HMP at 3 HMP settings: high flow (HF); low flow (LF); low flow + O(2) (300 mm Hg) (LFO). HMP livers were perfused via the hepatic artery (HA) and portal vein (PV) with KPS-1 TM at 4 degrees C to 6 degrees C for 24 hours with HF: PV: 3 to 5 mm Hg, 1 mL/g liver/min for HA and 25 mm Hg; LF: PV: 3 to 5 mm Hg, 0.5 ml/g liver/min with HA: 20 mm Hg. Morphology and ATP levels were measured in preserved liver tissues.

RESULTS

Throughout the SCS preservation, livers remained intact. In HMP livers, vacuoles appeared after 4 hours of preservation in the HF group and after 12 hours in the LF livers. LFO livers remained intact with limited vacuoles. Compared to SCS, HMP livers showed dilated sinusoids, particularly in the HF group. ATP remained relatively constant or even increased during HMP, particularly in the LF group, whereas ATP decreased after SCS.

CONCLUSION

Among the various HMP settings, HMP with LFO was superior. ATP levels were the highest in LF. In contrast with all HMP groups, SCS showed the lowest ATP levels, indicating that HMP has the potential to better preserve energy stores.

Histomorphometric analysis of rabbit calvarial bone: storage in saline solution versus storage in platelet-poor plasma

PURPOSE

In reconstructive procedures harvested bone grafts are often temporarily stored in extraoral media while the recipient site is prepared. The aim of the present study was to analyze histomorphometrically osteocytes in calvarial bone grafts stored in either physiologic saline solution or platelet-poor plasma (PPP).

MATERIALS AND METHODS

Calvarial bone fragments were obtained from 12 rabbits and fixed immediately in formalin (control) or stored in PPP or in saline solution for 30 minutes prior to fixation. All specimens were decalcified and embedded in glycol methacrylate. A differential osteocyte count (normal osteocytes, abnormal osteocytes, and empty lacunae) was performed for the sections and submitted to analysis of variance (ANOVA) and the Fisher least-square-difference (LSD) test. P < .05 was considered significant.

RESULTS

The histomorphometric analysis demonstrated statistically significant differences among the groups (control, PPP, saline) for all analyzed parameters (P < .05). The median number of normal osteocytes observed was 31.8 +/- 2.3 for the control group, 29.7 +/- 4.2 for the PPP group, and 19.1 +/- 4.6 for the saline group. The median number of abnormal osteocytes observed was 14.7 +/- 3.9 for the saline group, 8.7 +/- 2.3 for the PPP group, and 7.0 +/- 2.3 for the control group. The median number of empty lacunae observed was 12.9 +/- 4.7 for the saline group, 8.5 +/- 2.4 for the PPP group, and 6.9 +/- 2.3 for the control group.

CONCLUSION

The current study has shown that PPP is a better storage medium for osteocyte preservation than physiologic saline solution. The best results were observed in the control group. (More than 50 references.)

Kinetics of PME/Pi in pig kidneys during cold ischemia

Quality assessment of renal grafts via (31)P magnetic resonance spectroscopy (MRS) has been investigated since 1986. As ATP concentrations decay rapidly during cold ischemia, the ratio of phosphomonoesters (PME) to inorganic phosphate (Pi(O)) within the organ (PME/Pi(O)) is commonly used as a quality marker and is considered to be the most reliable parameter. MRS did not lead to any delay in the transplantation procedure since it was performed during the time necessary for immunological matching (cross-match). Differences in the time period until transplantation call for extrapolation of the measured ratio to the end of cold ischemia before correlating with graft performance after transplantation. Therefore, quantitative determination of PME/Pi(O) kinetics is essential. As a model for metabolite decay in human renal grafts, pig kidneys obtained from a slaughterhouse were monitored for up to 80 h via (31)P MRS at 2 T. By employing chemical shift imaging (CSI) with a spatial resolution of approximately 1 x 1 x 4 cm(3), it was possible to reduce partial volume effects significantly. The improved spectral resolution gained through CSI enabled reliable PME/Pi(O) ratios to be determined only from those voxels containing renal tissue. Spectra were fitted automatically using the magnetic resonance user interface (MRUI), with prior knowledge obtained from unlocalized spectra when necessary. A monoexponential time dependence of PME/Pi(O) for histidine-tryptophane-alpha-ketoglutarate (HTK)-perfused kidneys during cold ischemia was observed, and the determined value of the decay constant alpha was 0.0099 +/- 0.0012 h(-1). In University of Wisconsin solution (UW)-perfused kidneys, an alpha of 0.0183 +/- 0.0053 h(-1) was determined. Determination of the decay constant enables a usable extrapolation of PME/Pi(O) for quality assessment of UW perfusion and a reliable extrapolation for HTK-perfused human renal grafts.

Electrical Impedance of the Liver During Experimental Long-Term Liver Preservation

Measurements of electrical impedance were performed to assess ischemic damage in the rabbit liver during long-term preservation with University of Wisconsin (UW) or histidine-tryptophan-ketoglutarate (HTK) solution. The impedance was measured at a frequency of 200 Hz after in situ perfusion and after cold storage for 24 and 48 hours in UW or HTK solution (six livers per group). Z(200 Hz) was significantly higher (P < .01) after 48 compared with 24 hours of cold storage with both protection solutions without significant differences between the livers preserved with both solutions. Electrical impedance was observed to be a sensitive indicator of liver damage during long-term protection, showing similar preservation quality for both preservation solutions.

Cold preservation of isolated hepatocytes in UW solution: experimental studies on the respiratory activity at 0 degrees C

To date, little attention has been paid to the role of the gas milieu in preservation solutions and its effect on cell viability. Dissolved O2 in the preservation media may be an important parameter to consider. In this study we polarographically measured the O2 concentration in air-equilibrated UW solution at 0 degrees C, as well as the respiratory activity of isolated hepatocytes cold-preserved in this solution up to 72 hours. To perform measurements at 0 degrees C, it was first necessary to characterize the sensor behavior at low temperatures. We verified that the sensor response is still linear at this temperature but the rate of response is significantly slower. The O2 solubility in UW-air solution at 0 degrees C was determined using a modified physical method and it was 410 microM O2, which, as expected, is lower than the solubility in water at the same temperature (453 microM O2). Isolated hepatocytes cold-stored in UW-air solution retained a measurable respiratory activity during a period of 72 hours. The O2 consumption rate was 0.48 +/- 0.13 nmol/O2/min/10(6) cells, which represents 1% of the control value at 36 degrees C (61.46 +/- 14.61 nmol/O2/min/10(6) cells). The respiratory activity and cell viability were well maintained during the preservation period. At present, preservation conditions need to be improved for cells to remain functionally active. Dissolved O2 may be required for energy re-synthesis but it also leads to an increment in reactive oxygen species. The O2 concentration in the preservation solution should be carefully controlled, reaching a compromise between cell requirement and toxicity.

Experimental study on the cryopreservation of LLC-PK1 epithelial cells with hypoxic UW solution

The effects of oxygen partial pressure on cryopreservation of the cells with organ preservation solution were explored. Hypoxic UW solution was made by purging the UW solution with argon. The pig proximal tubule epithelial cells (LLC-PK1 cells) were cryopreserved in hypoxic UW solution (Ar-UW group) or standard UW solution (UW group) at 4 degrees C for 48 h. Trypan blue staining and LDH detection were performed to evaluate the injury of the cells. The results showed that the oxygen partial pressure in Ar-UW group was significantly declined from 242+/-6 mmHg to 83+/-10 mmHg. After cryopreservation at 4 degrees C for 48 h, LDH leakage rate and Trypan blue-stained rate in Ar-UW group were (11.3+/-3.4)% and (10.5+/-4.7)%, respectively, which were significantly lower than in UW group [(49.5+/-6.9)% and (47.6+/-9.3)% respectively, both P<0.01]. It was concluded that lower oxygen partial pressure of UW solution was more beneficial to the cryopreservation of LLC.

Sole use of sucrose in human sperm cryopreservation

Glycerol alone or in combination with other additives is one of the most widely used and successful cryoprotectants for human sperm. The glycerol method requires rigorous post thaw sample washing for use in ART and this may lead to low sperm yield from oligospermic samples. In this study the feasibility of the use of sucrose in sperm cryopreservation was explored. Sucrose as cryoprotectant was combined with direct plunging of sample into liquid nitrogen (vitrification) as a freezing method. Sucrose treated sperm from normozoospermic and severly oligozoospermic samples underwent rapid freeze and thaw. Motility and viability were evaluated before freezing (after sucrose equilibration) as well as post freezing (after thaw). The 100 mM concentration of sucrose showed better cryoprotectant features compared to that of higher concentrations (200-1000 mM). Sucrose (100 mM)treated sperm maintained low but acceptable motility (30%) and satisfactory viability (60%) after freezing and thawing. The cryoprotectant capacity of sucrose for normozoospermic and oligozoospermic samples were identical. The sucrose method utilizes rapid freezing of a micro volume of sample and thus quickly freezes, thaws, and maximizes recovery of the sperm from the sample.