pancreatic islet transplantation is a physiologically advantageous and minimally invasive procedure for the treatment of type 1 diabetes mellitus ( 1 ) .
the success rate of islet transplantation has been improved by transplanting a higher mean islet mass prepared from two to four donor pancreases and using glucocorticoid - free immunosuppressants ( 1 , 2 ) . however , a shortage of donors and the use of potentially islet - toxic immunosuppressants are the main hurdles to successful islet transplantation .
few data are available on islet isolation from the pancreas of asian people , and most of the guidelines on islet isolation techniques are based on the procedures used on western subjects .
reports on allogeneic islet transplantation alone in the korean population are lacking . according to data from the korean network for organ sharing
, 10 cases of allogeneic islet transplantation have been performed , and most were islet - after - kidney transplantations ( 3 ) .
several autologous islet transplantations have been reported ( 4 ) , but islet isolation was performed using a living - donor pancreas and an inadequate quantity of isolated islets was not a limitation to performing the transplantation . here , we report on a case of allogeneic islet transplantation alone , using a marginal dose from a single - donor pancreas in a korean patient with type 1 diabetes mellitus .
a 59-yr - old woman who had been diagnosed with type 1 diabetes mellitus for 25 yr , suffered from recurrent severe hypoglycemia and hypoglycemic unawareness since october 2011 .
her body weight was 52 kg and her body mass index ( bmi ) was 20.31 kg / m .
fasting and postprandial serum c - peptide concentrations were 0.07 ng / ml and 0.23 ng / ml , respectively .
she had visited the emergency room twice complaining of decreased consciousness related to severe hypoglycemia ( < 50 mg / dl ) in the previous year .
she did not experience hypoglycemic symptoms until her blood glucose level decreased to 50 mg / dl .
her total insulin requirement was 34 u / day , and her glycated hemoglobin ( hba1c ) level ranged from 7.8% to 9.6% with a mean value of 8.54% in the preceding 2 yr . the estimated glomerular filtration rate ( egfr ) was 91.67 ml / min/1.73 m and albumin to creatinine ratio ( acr ) was 16.45 mg / g .
the pancreas was procured from a 49-yr - old brain - death donor with a bmi of 23.13 kg / m .
the organ was transported in chilled histidine - tryptophan - ketoglutarate solution and transferred to the good manufacturing practice facility .
the pancreas was distended by controlled ductal perfusion with liberase human islet enzyme ( roche diagnostics , indianapolis , usa ) and digested mechanically in a ricordi chamber .
pancreatic tissue density was tested before purification using a cobe 2991 cell processor ( gambro bct inc . , lakewood , co , usa ) to predict the pancreatic tissue density .
prepurification gradient tests were performed using a ficoll ( biochrom , berlin , germany)-based standard gradient ( 1.100 - 1.077
louis , mo , usa)-based gradient-1 ( 1.100 - 1.085 - 1.060 g / cm ) and optiprep - based gradient-2 ( 1.090 - 1.075 - 1.050 g / cm ) .
the tests showed little differences in the density and produced a single layer of islet - acinar cell mixture .
by contrast , a gradient test using optiprep - based gradient-3 ( 1.080 - 1.065 - 1.040 g / cm ) produced two distinct layers of the different cell types .
the total amount of purified islets was 216,500 islet equivalents ( ieq ) ( 4,163 ieq / recipient body weight in kg ) , which is the minimally adequate quantity for transplantation ( 5 ) .
the purity of the isolated islets was 79.6% , and the islet viability was > 90% .
glucose stimulated insulin secretion of isolated islet was tested in vitro and showed an insulin concentration of 10.1 u / ml at low ( 2.8 mm ) glucose media and 17.1 u / ml at high ( 16.8 mm ) glucose media during 1 hr each .
the patient was sedated and a percutaneous transhepatic approach was used to access to the portal vein under fluoroscopic guidance .
doppler ultrasonography of the portal vein was performed within 24 hr after transplantation , and no definite evidence of flow disturbance was observed .
the immunosuppressive regimen was based on that previously described in the edmonton protocol ( 5 ) . instead of daclizumab
, basiliximab was given intravenously at a dose of 20 mg 2 hr before islet transplantation and 4 days after transplantation .
sirolimus was administered administered once daily to achieve a target trough therapeutic range of 12 - 15 ng / ml for the first 3 months , after which the target trough range was planned to be lowered to 7 - 12 ng / ml .
tacrolimus was administered twice daily and adjusted to achieve a target trough level of 3 - 6 ng / ml .
one month after transplantation , the dosage of sirolimus was reduced because of systemic mucositis and leukopenia , and this dosage was maintained at the trough level of 5 - 9 ng / ml .
the islet transplantation protocol was approved by the institutional review board of the catholic university of korea ( no .
after islet transplantation , the patient 's insulin requirement decreased to 22 u / day , which was about 65% of the previous requirement ( fig .
fasting and postprandial c - peptide concentrations improved to 0.25 ng / ml and 0.44 ng / ml , respectively , at 2 months after transplantation . the hba1c level improved to 7.3% at 3 months after transplantation .
self - monitored blood glucose concentration was measured four times a day ( before each meal and at bedtime ) , and the results showed marked improvement in the frequencies of both hypoglycemia and extreme hyperglycemia after transplantation ( fig .
2 ) . before transplantation , she experienced severe hypoglycemia ( < 50 mg / dl ) on average twice a month .
however , she did not experience further severe hypoglycemia and became aware of hypoglycemia at a glucose concentration of 70 mg / dl .
we calculated the glycemic risk assessment diabetes equation ( grade ) score to assess the glycemic variability and the percentage contribution of hypoglycemia events , before and at 3 and 9 months after the transplantation ( 6 ) .
also the average daily risk range ( adrr ) index was calculated ; the values are stratified into three categories : low risk < 20 ; moderate risk , 20-40 ; and high risk > 40 ( 7 , 8) . before the transplantation ,
the grade score was 10.31 with 28.5% of hypoglycemia ( < 70 mg / dl ) events , and improved to grade score of 7.94 with 2.4% of hypoglycemia events and 5.99 with 2.1% of hypoglycemia events at 3 and 9 months after the transplantation , respectively .
similarly , the adrr index was 26.88 before the transplantation and improved to 17.56 and 14.60 at 3 and 9 months after transplantation , respectively .
currently ( about 9 months after the transplantation ) , her hba1c is 7.8% , and fasting and postprandial c - peptide concentrations are 0.20 and 0.43 ng / ml , respectively .
there is no evidence of leukopenia and her renal function is in normal range with an egfr of 106.04 ml / min/1.73 m.
a 59-yr - old woman who had been diagnosed with type 1 diabetes mellitus for 25 yr , suffered from recurrent severe hypoglycemia and hypoglycemic unawareness since october 2011 .
her body weight was 52 kg and her body mass index ( bmi ) was 20.31 kg / m .
fasting and postprandial serum c - peptide concentrations were 0.07 ng / ml and 0.23 ng / ml , respectively .
she had visited the emergency room twice complaining of decreased consciousness related to severe hypoglycemia ( < 50 mg / dl ) in the previous year .
she did not experience hypoglycemic symptoms until her blood glucose level decreased to 50 mg / dl .
her total insulin requirement was 34 u / day , and her glycated hemoglobin ( hba1c ) level ranged from 7.8% to 9.6% with a mean value of 8.54% in the preceding 2 yr . the estimated glomerular filtration rate ( egfr ) was 91.67 ml / min/1.73 m and albumin to creatinine ratio ( acr ) was 16.45 mg / g .
the pancreas was procured from a 49-yr - old brain - death donor with a bmi of 23.13 kg / m .
the organ was transported in chilled histidine - tryptophan - ketoglutarate solution and transferred to the good manufacturing practice facility .
the pancreas was distended by controlled ductal perfusion with liberase human islet enzyme ( roche diagnostics , indianapolis , usa ) and digested mechanically in a ricordi chamber .
pancreatic tissue density was tested before purification using a cobe 2991 cell processor ( gambro bct inc . ,
prepurification gradient tests were performed using a ficoll ( biochrom , berlin , germany)-based standard gradient ( 1.100 - 1.077
louis , mo , usa)-based gradient-1 ( 1.100 - 1.085 - 1.060 g / cm ) and optiprep - based gradient-2 ( 1.090 - 1.075 - 1.050 g / cm ) .
the tests showed little differences in the density and produced a single layer of islet - acinar cell mixture .
by contrast , a gradient test using optiprep - based gradient-3 ( 1.080 - 1.065 - 1.040 g / cm ) produced two distinct layers of the different cell types .
the total amount of purified islets was 216,500 islet equivalents ( ieq ) ( 4,163 ieq / recipient body weight in kg ) , which is the minimally adequate quantity for transplantation ( 5 ) .
the purity of the isolated islets was 79.6% , and the islet viability was > 90% .
glucose stimulated insulin secretion of isolated islet was tested in vitro and showed an insulin concentration of 10.1 u / ml at low ( 2.8 mm ) glucose media and 17.1 u / ml at high ( 16.8 mm ) glucose media during 1 hr each .
the islet transplantation was performed in november 2013 . the patient was sedated and a percutaneous transhepatic approach was used to access to the portal vein under fluoroscopic guidance .
doppler ultrasonography of the portal vein was performed within 24 hr after transplantation , and no definite evidence of flow disturbance was observed .
the immunosuppressive regimen was based on that previously described in the edmonton protocol ( 5 ) . instead of daclizumab
, basiliximab was given intravenously at a dose of 20 mg 2 hr before islet transplantation and 4 days after transplantation .
sirolimus was administered administered once daily to achieve a target trough therapeutic range of 12 - 15 ng / ml for the first 3 months , after which the target trough range was planned to be lowered to 7 - 12 ng / ml .
tacrolimus was administered twice daily and adjusted to achieve a target trough level of 3 - 6 ng / ml .
one month after transplantation , the dosage of sirolimus was reduced because of systemic mucositis and leukopenia , and this dosage was maintained at the trough level of 5 - 9 ng / ml .
the islet transplantation protocol was approved by the institutional review board of the catholic university of korea ( no .
after islet transplantation , the patient 's insulin requirement decreased to 22 u / day , which was about 65% of the previous requirement ( fig .
fasting and postprandial c - peptide concentrations improved to 0.25 ng / ml and 0.44 ng / ml , respectively , at 2 months after transplantation . the hba1c level improved to 7.3% at 3 months after transplantation .
self - monitored blood glucose concentration was measured four times a day ( before each meal and at bedtime ) , and the results showed marked improvement in the frequencies of both hypoglycemia and extreme hyperglycemia after transplantation ( fig .
2 ) . before transplantation , she experienced severe hypoglycemia ( < 50 mg / dl ) on average twice a month .
however , she did not experience further severe hypoglycemia and became aware of hypoglycemia at a glucose concentration of 70 mg / dl .
we calculated the glycemic risk assessment diabetes equation ( grade ) score to assess the glycemic variability and the percentage contribution of hypoglycemia events , before and at 3 and 9 months after the transplantation ( 6 ) .
also the average daily risk range ( adrr ) index was calculated ; the values are stratified into three categories : low risk < 20 ; moderate risk , 20-40 ; and high risk > 40 ( 7 , 8) . before the transplantation ,
the grade score was 10.31 with 28.5% of hypoglycemia ( < 70 mg / dl ) events , and improved to grade score of 7.94 with 2.4% of hypoglycemia events and 5.99 with 2.1% of hypoglycemia events at 3 and 9 months after the transplantation , respectively .
similarly , the adrr index was 26.88 before the transplantation and improved to 17.56 and 14.60 at 3 and 9 months after transplantation , respectively .
currently ( about 9 months after the transplantation ) , her hba1c is 7.8% , and fasting and postprandial c - peptide concentrations are 0.20 and 0.43 ng / ml , respectively .
there is no evidence of leukopenia and her renal function is in normal range with an egfr of 106.04 ml / min/1.73 m.
to our knowledge , this is the first reported case on allogeneic islet transplantation alone in korea .
although insulin independence was not achieved , the patient showed stabilized blood glucose concentration , reduced insulin dosage and reversal of hypoglycemic unawareness , even with a marginal dose of islets and reduced immunosuppressant .
there are only a few reports on islet transplantation in asian subjects . according to the collaborative islet transplantation registry ,
centers from north america , europe and australia are registered , but none from asian countries ( 9 ) . when islets are purified with a cobe
however , this method does not appropriately adjust for interpancreatic variations in exocrine and islet tissue density , which is influenced by donor characteristics , the secretory status of exocrine cells , and the islet isolation procedure ( 10 ) .
predicting pancreatic tissue density using prepurification density tests may improve the islet isolation yield , as we performed in this case . hering et al .
( 11 ) reported on allogeneic islet transplantation using marginal dose islets ( average of 7,271 ieq / kg ) from a single donor pancreas along with potent induction immunotherapy ( antithymocyte globulin , daclizumab and etanercept ) .
however , our patient underwent islet transplantation with only a marginal quantity of islets ( 4,163 ieq / kg ) with reduced immunosuppressant . in conclusion , this is the first reported case on successful islet transplantation alone in a korean patient with type 1 diabetes .
although insulin independence was not achieved , the patient showed stabilized blood glucose concentration , reduced insulin dosage and reversal of hypoglycemic unawareness , even with a marginal dose of islets and reduced immunosuppressant .
 pancreatic islet transplantation is a physiologically advantageous and minimally invasive procedure for the treatment of type 1 diabetes mellitus . here 
 , we describe the first reported case of successful allogeneic islet transplantation alone , using single - donor , marginal - dose islets in a korean patient . 
 a 59-yr - old patient with type 1 diabetes mellitus , who suffered from recurrent severe hypoglycemia , received 4,163 islet equivalents / kg from a single brain - death donor . 
 isolated islets were infused intraportally without any complications . 
 the immunosuppressive regimen was based on the edmonton protocol , but the maintenance dosage was reduced because of mucositis and leukopenia . although insulin independence was not achieved , the patient showed stabilized blood glucose concentration , reduced insulin dosage and reversal of hypoglycemic unawareness , even with marginal dose of islets and reduced immunosuppressant . 
 islet transplantation may successfully improve endogenous insulin production and glycemic stability in subjects with type 1 diabetes mellitus.graphical abstract 
Graphical Abstract
INTRODUCTION
CASE DESCRIPTION
Islet transplantation recipient
Islet isolation using prepurification gradient tests
Islet transplantation and immunosuppressant
Assessment of glycemic control after islet transplantation
DISCUSSION