Upregulated expression of human membrane type-5 matrix metalloproteinase in kidneys from diabetic patients

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix (ECM). The membrane-type matrix metalloproteinases (MT-MMPs) are a new family of MMPs that differ from other MMPs in that they have a transmembrane domain that anchors them to the cell surface. MT-MMPs have been shown to function as receptors and activators for other MMPs and to localize extracellular matrix proteolysis at the pericellular region. Here we report on mRNA and protein expression of the fifth human MT-MMP (MT5-MMP), a 64-kDa protein that is capable of converting pro-MMP-2 to its active form, in human kidney as well as its upregulation in diabetes. We also demonstrate upregulation of the active form of MMP-2 in kidney samples from patients with diabetes. Through immunohistochemistry, MT5-MMP expression was localized to the epithelial cells of the proximal and distal tubules, the collecting duct, and the loop of Henle. Furthermore, the tubular epithelial cells that expressed MT5-MMP were associated with tubular atrophy. Because renal tubular atrophy is a significant factor in the pathogenesis of diabetic nephropathy and renal failure and the molecular mechanisms regulating this process remain unknown, it is hypothesized that the elevated expression of MT5-MMP contributes to the activation of pro-MMP-2, which participates in the remodeling of the proximal and distal tubules as well as in the collecting duct. These results provide the first evidence of the expression of a MT-MMP in diabetes and suggest a novel role for MT5-MMP in the pathogenesis of renal tubular atrophy and end-stage renal disease.

Differential modulation of endothelin ligand-induced contraction in isolated tracheae from endothelin B (ET(B)) receptor knockout mice

The role of endothelin B (ET(B)) receptors in mediating ET ligand-induced contractions in mouse trachea was examined in ET(B) receptor knockout animals. Autoradiographic binding studies, using [(125)I]-ET-1, confirmed the presence of ET(A) receptors in tracheal and bronchial airway smooth muscle from wild-type (+/+) and homozygous recessive (-/-) ET(B) receptor knockout mice. In contrast, ET(B) receptors were not detected in airway tissues from (-/-) mice. In tracheae from (+/+) mice, the rank order of potencies of the ET ligands was sarafotoxin (Stx) S6c>ET-1>ET-3; Stx S6c had a lower efficacy than ET-1 or ET-3. In tissues from (-/-) mice there was no response to Stx S6c (up to 0.1 microM), whereas the maximum responses and potencies of ET-1 and ET-3 were similar to those in (+/+) tracheae. ET-3 concentration-response curve was biphasic in (+/+) tissues (via ET(A) and ET(B) receptor activation), and monophasic in (-/-) preparations (via stimulation of only ET(A) receptors). In (+/+) preparations SB 234551 (1 nM), an ET(A) receptor-selective antagonist, inhibited the secondary phase, but not the first phase, of the ET-3 concentration-response curve, whereas A192621 (100 nM), an ET(B) receptor-selective antagonist, had the opposite effect. In (-/-) tissues SB 234551 (1 nM), but not A192621 (100 nM), produced a rightward shift in ET-3 concentration-response curves. The results confirm the significant influence of both ET(A) and ET(B) receptors in mediating ET-1-induced contractions in mouse trachea. Furthermore, the data do not support the hypothesis of atypical ET(B) receptors. In this preparation ET-3 is not an ET(B) receptor-selective ligand, producing contractions via activation of both ET(A) and ET(B) receptors.

Targeted disruption of the endothelin-B-receptor gene attenuates inflammatory nociception and cutaneous inflammation in mice

Endothelin-1 (ET-1) has been suggested to have a potential function as an inflammatory mediator. The study reported here assessed the putative inflammatory/nociceptive actions of the ET isopeptides using endothelin-B (ET(B))-receptor knockout (KO) mice and ET(A)- (SB 234551) and ET(B)- (A192621) selective antagonists. Phenylbenzoquinone (PBQ)-induced algesia was evident in the wild-type (WT) ET(B) (+/+) mice, attenuated by 80% in the heterozygous ET(B) (+/-) mice, and absent in the ET(B) (-/-) homozygotes. This was reproduced pharmacologically in WT ET(B) (+/+) mice where the algesic effect of PBQ was inhibited 74% by A192621, but unaffected by SB 234551 (both at 25 mg/kg p.o.). Similar observations were made in a model of cutaneous inflammation: ET(B) (+/+) mice had a marked inflammatory response to topical arachidonic acid, ET(B) (+/-) and ET(B) (-/-) mice had significantly reduced edema responses (37% and 65% inhibition). Neutrophil infiltration was reduced in the ET(B) (+/-) and ET(B) (-/-) mice (51% and 65% reduction, respectively). Topical administration of A192621 (500 microg/ear) inhibited arachidonic acid-induced swelling (39%) in WT ET(B) (+/+) mice. Collectively, these results support a role for the ET(B)-receptor in the mediation of inflammatory pain and cutaneous inflammatory responses. As such, the development of ET(B)-receptor-selective antagonists may be of therapeutic utility in the treatment of inflammatory disorders.

Microencapsulation of neonatal porcine islets: protection from human antibody/complement-mediated cytolysis in vitro and long-term reversal of diabetes in nude mice

BACKGROUND

Recently, we have developed a simple and reliable method to efficiently isolate large numbers of neonatal porcine islets (NPI). We and others have shown that NPI are susceptible to cytolysis by the activation of human complement in vitro. Microencapsulation of islets may be one strategy to protect NPI from this form of rejection. We examined whether microencapsulation can prevent lysis of NPI induced by human antibody and complement in vitro and also assessed their ability to reverse hyperglycemia in diabetic nude mice.

METHODS

NPI were microencapsulated with purified alginate, cultured for 2 days, then tested for sensitivity to fresh human serum using an established in vitro cytotoxicity assay or transplanted into alloxan-induced diabetic nude mice.

RESULTS

Incubation of nonencapsulated NPI for 24 hr in the presence of fresh human serum resulted in a 53% loss of cellular insulin content, a 51% reduction in recoverable DNA content, and a marked reduction of insulin secretory responsiveness when compared with controls cultured in heat-inactivated human serum. In contrast, exposure of encapsulated islets to fresh human serum had no cytotoxic effect on the islets. Transplantation of 2000 encapsulated NPI i.p. into diabetic nude mice (n=16) corrected hyperglycemia in all mice within 8 weeks. Similar results were obtained when 2000 nonencapsulated NPI were implanted under the kidney capsule (n=10); however recipients of nonencapsulated NPI placed i.p. failed to obtain euglycemia and survived for only 3 weeks posttransplantation.

CONCLUSION

Microencapsulation protects NPI from the cytotoxic effects of human antibody and complement and allows for long-term reversal of diabetes in nude mice.

Study on pottical type, palmar and plantar digital formulae, hand clasping, arm folding, handedness, leg folding and stride type in the Daur population, China

The pottical type, palmar and plantar digital formulae, hand clasping, arm folding, handedness, leg folding and stride type have been investigated on a sample of 143 male and 160 female students of the Daur population of Molidawa Banner, Inner Mongolia. The results of this study are the following: 1. the frequency of the hyperextensive pottical type is 49.17%, the relative length of index over annularis 12.21%, right hand clasping 45.87%, right arm folding 49.50%, right handedness 94.39%, right leg folding 72.28% and right stride type 44.88%, 2. pottical type, hand clasping, handedness, leg folding and stride type do not show significant sex differences, 3. there are some relations between hand clasping and arm folding as well as between arm folding and stride type, 4. compared with other population groups, the Daur population shows a low frequency of right hand clasping, a moderate frequency of right arm folding and a low frequency of left handedness.

Murine Siva-1 and Siva-2, alternate splice forms of the mouse Siva gene, both bind to CD27 but differentially transduce apoptosis

CD27, a member of the TNFR family known to provide essential co-stimulatory signals for T cell growth and B cell Ig synthesis, can also mediate cell death. Using the CD27 cytoplasmic tail as the bait in yeast two hybrid assay, we previously cloned human Siva, a pro-apoptotic molecule. Here we report the characterization of the mouse Siva gene as a 4 kb sequence containing 4 exons and 3 introns. RT-PCR has revealed the presence of two forms of mouse Siva mRNA, the longer full length form Siva-1 and the shorter Siva-2 lacking the sequence coded by exon 2. Immunoblotting with anti-Siva (human) antibodies clearly demonstrate the presence of both Siva-1 and Siva-2. Cotransfection experiments in 293T cells reveal that mouse CD27 receptor can interact with both forms of Siva. Although mouse Siva-1 can trigger apoptosis in Rat-1 cells and in some of the mouse cell lines in transient transfection experiments, similar to the observation made with human Siva, intriguingly its alternate splice form, Siva-2 appears to be much less toxic. It is therefore likely that Siva-2 could regulate the function of Siva-1.

Endothelin B receptor modulates inflammatory pain and cutaneous inflammation

The role of endothelin B (ET(B)) receptors in inflammation and nociception was examined using ET(B) receptor knockout mice. Genotyping studies were used with tissues from ET(B)((+/+)), ET(B)((+/-)), and ET(B)((-/-)) mice to confirm the loss of ET(B) receptors. Algesia induced by phenylbenzoquinone was evident in the (+/+) mice, reduced by approximately 80% in the (+/-) mice, and absent in the (-/-) mice. Phenylbenzoquinone-induced algesia in (+/+) mice was inhibited 74% by the ET(B) receptor-selective antagonist A192621 (25 mg/kg p.o.), but unaffected by the ET(A) receptor-selective antagonist SB 234551 (25 mg/kg p.o.). Noninflammatory pain, induced by hotplate, was equivalent between (+/+) and (-/-) mice. The cutaneous inflammatory response to topical arachidonic acid (AA) also was evaluated. Whereas (+/+) mice had a marked inflammatory response to AA, the (+/-), and (-/-) mice had significantly reduced fluid phase responses (37 and 65% inhibition, respectively). Neutrophil infiltration also was reduced in the (+/-) and (-/-) mice (51 and 65% reduction, respectively). Topical administration of A192621 (500 microg/ear) in (+/+) mice inhibited AA-induced swelling (39%), whereas SB 234551 (500 microg/ear) was without effect. Collectively, these results implicate the ET(B) receptor in mediation of inflammatory pain and cutaneous inflammatory responses in mice.

Human urotensin-II is a potent vasoconstrictor and agonist for the orphan receptor GPR14

Urotensin-II (U-II) is a vasoactive 'somatostatin-like' cyclic peptide which was originally isolated from fish spinal cords, and which has recently been cloned from man. Here we describe the identification of an orphan human G-protein-coupled receptor homologous to rat GPR14 and expressed predominantly in cardiovascular tissue, which functions as a U-II receptor. Goby and human U-II bind to recombinant human GPR14 with high affinity, and the binding is functionally coupled to calcium mobilization. Human U-II is found within both vascular and cardiac tissue (including coronary atheroma) and effectively constricts isolated arteries from non-human primates. The potency of vasoconstriction of U-II is an order of magnitude greater than that of endothelin-1, making human U-II the most potent mammalian vasoconstrictor identified so far. In vivo, human U-II markedly increases total peripheral resistance in anaesthetized non-human primates, a response associated with profound cardiac contractile dysfunction. Furthermore, as U-II immunoreactivity is also found within central nervous system and endocrine tissues, it may have additional activities.

Intraductal collagenase delivery into the human pancreas using syringe loading or controlled perfusion

Effective intraductal delivery of the enzyme collagenase into the pancreas is crucial to the subsequent ability to isolate viable islets. Most clinical islet transplant centers load the enzyme into the pancreas by retrograde injection using a syringe following cannulation of the pancreatic duct. An alternative approach is to perfuse the pancreas via the pancreatic duct with collagenase solution using a recirculating perfusion device system. This provides control over perfusion pressures and collagenase temperature. This study reports on our evaluation of the delivery of Liberase-HI into the pancreas of 14 consecutive adult multiorgan cadaveric donors. Alternate glands were procured and processed using an identical protocol with the exception of collagenase delivery. The first group of pancreases was loaded using the perfusion technique where cold (4 degrees C) Liberase-HI was perfused at 80 mmHg for 5 min after which the pressure was increased to 180 mmHg. The collagenase solution was then slowly warmed to 35 degrees C, transferred to the dissociation chamber and mechanically dissociated, and then purified using discontinuous gradients of Ficoll. Pancreases in the second group were loaded with collagenase (28-32 degrees C) using the syringe technique before mechanical dissociation and purification. There were no significant differences in pancreas cold ischemia, donor age, body mass index, maximum blood glucose, or serum amylase of the donors between the two groups. Mean collagenase digestion time in the digestion chamber was not different between the two groups; however, the amount of undigested tissue remaining after dissociation was significantly higher in the syringe-loaded group (15.3 +/- 2.6 g vs. 4.6 +/- 2.1 g, mean +/- SEM, p < 0.05). Postdigestion recovery of islets was 471 +/- 83 x 10(3) IE in the perfusion group compared with 391 +/- 57 x 10(3) IE for the syringe-loaded group. Postpurification recovery was higher in the perfused group (379 +/- 45 vs. 251 +/- 28 x 10(3) IE, p < 0.05, two-tailed paired t-test). No difference in in vitro islet viability was observed between the two groups following glucose perifusion with the calculated stimulation index of 4.6 +/- 0.6 for the perfusion group and 4.2 +/- 0.7 for the syringe-loaded group. Controlled perfusion via the pancreatic duct allows the effective delivery of the enzyme achieving maximal distension to all regions of the pancreas leading to an increased recovery of the islets with no detrimental effect on subsequent in vitro islet function.

IEX-1L, an apoptosis inhibitor involved in NF-kappaB-mediated cell survival

Transcription factors of the nuclear factor-kappaB/rel (NF-kappaB) family may be important in cell survival by regulating unidentified, anti-apoptotic genes. One such gene that protects cells from apoptosis induced by Fas or tumor necrosis factor type alpha (TNF), IEX-1L, is described here. Its transcription induced by TNF was decreased in cells with defective NF-kappaB activation, rendering them sensitive to TNF-induced apoptosis, which was abolished by transfection with IEX-1L. In support, overexpression of antisense IEX-1L partially blocked TNF-induced expression of IEX-1L and sensitized normal cells to killing. This study demonstrates a key role of IEX-1L in cellular resistance to TNF-induced apoptosis.

Induction and detection of apoptosis in human periphery blood T-cells

Freshly isolated, human peripheral blood T (PBT) cells are resistant to induction of apoptosis. In this study, however, we have shown that although small numbers of monocytes (Mo) are required for PBT cells to proliferate optimally in response to mitogenic challenge, a relatively higher percentage of Mo results in a significant decrease in PHA-, but not ConA-induced T-cell proliferation. Interestingly, the decrease in T-cell proliferation correlated to an increase in apoptotic cell death. Moreover, ConA-induced PBT-cells underwent apoptosis in the presence of PHA-pretreated Mo, suggesting a key role of monocyte activation in this system. This apoptosis-promoting effect of activated Mo appeared to depend on contact or close proximity between Mo and PBT-cells, rather than via soluble mediators. Despite an increase in apoptosis by the presence of high numbers of Mo, PHA-stimulated PBT-cells released IL-2 at elevated levels proportional to the increasing numbers of Mo in cultures. They also expressed activation marker CD69 and the IL-2R-gamma chain on the cell surface at comparable or higher levels in the presence of high versus low numbers of Mo. These data suggest that PBT-cells can embark on a normal early phase of activation prior to undergoing apoptosis, thereby providing a model system to study how T-cells are committed to either proliferation or activation-induced apoptosis.

CD27, a member of the tumor necrosis factor receptor family, induces apoptosis and binds to Siva, a proapoptotic protein

Members of the tumor necrosis factor receptor (TNFR) superfamily are important for cell growth and survival. In addition to providing costimulatory signals for cell proliferation, ligation of both TNFR1 and Fas can result in programmed cell death or apoptosis. The underlying mechanism requires an intact 80-aa stretch present in the cytoplasmic tails of both TNFR1 and Fas, termed the death domain (DD). Here we show that CD27, a member of the TNFR family, expressed on discrete subpopulations of T and B cells and known to provide costimulatory signals for T and B cell proliferation and B cell Ig production, can also induce apoptosis. Co-crosslinking of surface Ig receptors along with ligation of CD27 augments CD27-mediated apoptosis. Unlike TNFR1 and Fas, the cytoplasmic tail of CD27 is relatively short and lacks the DD. Using the yeast two-hybrid system, we have cloned a novel protein (Siva) that binds to the CD27 cytoplasmic tail. It has a DD homology region, a box-B-like ring finger, and a zinc finger-like domain. Overexpression of Siva in various cell lines induces apoptosis, suggesting an important role for Siva in the CD27-transduced apoptotic pathway.

Development of an automated computer-controlled islet isolation system

Before clinical islet transplantation can become an effective and reliable treatment for type 1 diabetic patients, there must be significant improvements in the methods employed for the isolation of islets of Langerhans. We have developed an automated cell extraction system (ACES), which allows computer control of the isolation process. As well, it incorporates a novel method of recombining dissociated pancreatic tissue. Following initial system design and testing to determine the optimal system configuration, a series of 12 consecutive canine islet isolations were performed. Pancreases were perfused with collagenase via the duct and dissociated and recombined using either the standard Ricordi-based protocol (group 1, n = 6) or dissociated and recombined using the ACES system (group 2, n = 6). A total of 90.8 +/- 21 x 10(3) islet equivalents (IE) (mean +/- SEM) were recovered in group 1 vs. 99 +/- 14 x 10(3) IE in group 2 (p = NS, student unpaired t-test). Following Ficoll purification the recovery was 56.2 +/- 14 x 10(3) IE for group 1 vs. 54.7 +/- 11 x 10(3) IE for group 2 (p = NS). Viability was equivalent with an 8.6-fold increase in insulin secretion for group 1 and an 8.8-fold increase for group 2 when the islets were exposed to high glucose solution supplemented with IBMX (3-isobutyl-1-methylxanthine) during static incubation. In vivo function was equivalent following transplantation of 2000 IE under the kidney capsule of alloxan-induced diabetic nude mice with five of six and five of seven mice surviving long-term (> 50 days posttransplant) (groups 1 and 2, respectively). This data shows that an entirely automated pancreatic islet extraction system can result in effective canine islet recovery without compromising islet yields and viability. The ACES system has several advantages over the standard isolation protocol. These include: 1) computer control and monitoring over all phases of the isolation, 2) a single-use sterile disposable tubing set, and 3) a novel method of tissue recombination.

A mitochondrial membrane protein defined by a novel monoclonal antibody is preferentially detected in apoptotic cells

Studies toward the biologic and molecular understanding of programmed cell death have been stimulated by the recent identification of genes and their products that regulate apoptosis. A panel of mAbs has been raised against dying cells in the present study by immunizing mice with apoptotic Jurkat cells. One of these Abs, anti-7A6, was found to react with apoptotic cells. Using ELISA or flow cytometry, little reactivity of anti-7A6 was observed in normal or digitonin-permeabilized human peripheral blood lymphocytes and a number of hemopoietic cell lines tested. The Ab, however, strongly reacted with these cells when they were induced to undergo apoptosis by irradiation or treatment with apoptosis-inducing agents. Cell sorting and DNA fragmentation experiments revealed that 7A6-positive cells, but not 7A6-negative cells, had apparent DNA fragments characteristic of cells undergoing apoptosis. By immunoblot, under reducing conditions, anti-7A6 detected a 38-kDa protein band in the cell lysates prepared from apoptotic cells. Immunoelectron microscopy showed the 7A6 Ag to be localized to the membrane of mitochondria in apoptotic Jurkat cells. These results indicate that anti-7A6 defines a novel epitope on the mitochondrial membrane protein that appears to be exposed on cells undergoing apoptosis, suggesting that the 7A6 molecule may be involved in the molecular cascade of apoptotic cell death.

A mitochondrial membrane protein defined by a novel monoclonal antibody is preferentially detected in apoptotic cells

Studies toward the biologic and molecular understanding of programmed cell death have been stimulated by the recent identification of genes and their products that regulate apoptosis. A panel of mAbs has been raised against dying cells in the present study by immunizing mice with apoptotic Jurkat cells. One of these Abs, anti-7A6, was found to react with apoptotic cells. Using ELISA or flow cytometry, little reactivity of anti-7A6 was observed in normal or digitonin-permeabilized human peripheral blood lymphocytes and a number of hemopoietic cell lines tested. The Ab, however, strongly reacted with these cells when they were induced to undergo apoptosis by irradiation or treatment with apoptosis-inducing agents. Cell sorting and DNA fragmentation experiments revealed that 7A6-positive cells, but not 7A6-negative cells, had apparent DNA fragments characteristic of cells undergoing apoptosis. By immunoblot, under reducing conditions, anti-7A6 detected a 38-kDa protein band in the cell lysates prepared from apoptotic cells. Immunoelectron microscopy showed the 7A6 Ag to be localized to the membrane of mitochondria in apoptotic Jurkat cells. These results indicate that anti-7A6 defines a novel epitope on the mitochondrial membrane protein that appears to be exposed on cells undergoing apoptosis, suggesting that the 7A6 molecule may be involved in the molecular cascade of apoptotic cell death.

Requirement of Fas(CD95), CD45, and CD11a/CD18 in monocyte-dependent apoptosis of human T cells

Our previous studies demonstrated that upon activation, monocytes (Mo) were able to sensitize peripheral blood T (PBT) cells to apoptosis induced by treatment with PMA. However, it is unknown what gene products provide the death signal to the sensitized PBT cells and how activated Mo enable PBT cells to become susceptible to apoptosis. Here, we show that PBT cells, but not Mo, express functional Fas ligand upon treatment with PMA. Moreover, this Mo-dependent T cell apoptosis could be blocked by a Fas-Ig fusion protein, as well as by a nonlytic mAb against Fas molecule. These results strongly suggest involvement of Fas-Fas ligand interaction in the death of PBT cells. Unlike Fas-induced apoptosis, however, Mo-dependent T cell death was completely inhibited by overexpression of the Bcl-2 protein, and PMA alone was sufficient to trigger apoptosis in T cells when Mo were included in culture. Furthermore, anti-CD11a, anti-CD18, or anti-CD45/CD45RA mAbs; could prevent PBT cells from death triggered by PMA plus Mo, suggesting that these Ags participate in the apoptotic process. The participation of CD45RA in the death of PBT cells was further demonstrated by the observation that the J45.01 cell line, a CD45-deficient variant of Jurkat cells, did not undergo apoptosis by this Mo-dependent mechanism. When transfected with cDNA encoding CD45RA, J45.01 cells acquired apoptotic response to PMA stimulation in the presence of Mo to a similar, but lesser, degree than normal Jurkat cells.

Requirement of Fas(CD95), CD45, and CD11a/CD18 in monocyte-dependent apoptosis of human T cells

Our previous studies demonstrated that upon activation, monocytes (Mo) were able to sensitize peripheral blood T (PBT) cells to apoptosis induced by treatment with PMA. However, it is unknown what gene products provide the death signal to the sensitized PBT cells and how activated Mo enable PBT cells to become susceptible to apoptosis. Here, we show that PBT cells, but not Mo, express functional Fas ligand upon treatment with PMA. Moreover, this Mo-dependent T cell apoptosis could be blocked by a Fas-Ig fusion protein, as well as by a nonlytic mAb against Fas molecule. These results strongly suggest involvement of Fas-Fas ligand interaction in the death of PBT cells. Unlike Fas-induced apoptosis, however, Mo-dependent T cell death was completely inhibited by overexpression of the Bcl-2 protein, and PMA alone was sufficient to trigger apoptosis in T cells when Mo were included in culture. Furthermore, anti-CD11a, anti-CD18, or anti-CD45/CD45RA mAbs; could prevent PBT cells from death triggered by PMA plus Mo, suggesting that these Ags participate in the apoptotic process. The participation of CD45RA in the death of PBT cells was further demonstrated by the observation that the J45.01 cell line, a CD45-deficient variant of Jurkat cells, did not undergo apoptosis by this Mo-dependent mechanism. When transfected with cDNA encoding CD45RA, J45.01 cells acquired apoptotic response to PMA stimulation in the presence of Mo to a similar, but lesser, degree than normal Jurkat cells.

Bulk cryopreservation of isolated islets of Langerhans

Current methods to isolate human islets of Langerhans are limited and multiple donors are required for successful reversal of longstanding Type 1 diabetes mellitus. Cryopreservation of isolated islets is an effective method of storing and pooling islets. Current cryopreservation protocols are cumbersome due to current practices of placing small aliquots of islets per individual freezer tube. In the present study, we examined the application of a blood freezer bag for the cryopreservation of isolated islets by slow cooling and rapid thawing. Freezing and thawing profiles generated using thermocouples placed inside a 500 mL Cryocyte (Baxter) blood freezer bag showed that a longer equilibration period at -7.4 degrees C was necessary to consistently achieve nucleation and cooling profiles similar to those observed in glass tubes. When known numbers of rat islets were placed in the freezer bag and the cryoprotectant dimethyl sulfoxide (DMSO) was added in a stepwise fashion and removed using a sucrose dilution, the islet recovery compared with glass tubes was 92 +/- 4.8 vs. 90 +/- 2.3% (n = 4, p = ns, Mann-Whitney U-test). When purified canine islets were cryopreserved in a single freezer bag or in multiple glass tubes, the recovery was similar (78.8 +/- 12.5% recovery for freezer bag vs. 82.3 +/- 5.3% for glass tubes; n = 6, p = ns). In vitro function was equivalent for both groups. The stimulation index of insulin release during glucose perifusion (stimulated over basal insulin secretion) for canine islets cryopreserved in a freezer bag vs. glass tubes was 3.2 +/- 1.0 and 2.3 +/- 1.3, respectively (n = 6, p = ns). These values were significantly lower than the nonfrozen control islets (6.9 +/- 2.4, p < 0.05). When 2000 canine islets cryopreserved in either a freezer bag, or glass tubes were transplanted into diabetic nude mice, the animals became and remained normoglycemic posttransplant. We conclude that the survival of freshly isolated canine islets cryopreserved in a single freezer bag is equivalent to the glass tube method. Bulk cryopreservation of islets in a single freezer bag will facilitate effective low temperature tissue banking to support ongoing clinical trials of islet transplantation.