Baosan Han

Middle segmental pancreatectomy: A safe and organ-preserving option for benign and low-grade malignant lesions

AIM To study the feasibility and safety of middle segmental pancreatectomy (MSP) compared with pancreaticoduodenectomy (PD) and extended distal pancreatectomy (EDP). METHODS We studied retrospectively 36 cases that underwent MSP, 44 patients who underwent PD, and 26 who underwent EDP with benign or low-grade malignant lesions in the mid-portion of the pancreas, between April 2003 and December 2009 in Ruijin Hospital. The perioperative outcomes and long-term outcomes of MSP were compared with those of EDP and PD. Perioperative outcomes included operative time, intraoperative hemorrhage, transfusion, pancreatic fistula, intra-abdominal abscess/infection, postoperative bleeding, reoperation, mortality, and postoperative hospital time. Long-term outcomes, including tumor recurrence, new-onset diabetes mellitus (DM), and pancreatic exocrine insufficiency, were evaluated. RESULTS Intraoperative hemorrhage was 316.1 ± 309.6, 852.2 ± 877.8 and 526.9 ± 414.5 mL for the MSP, PD and EDP groups, respectively (P < 0.05). The mean postoperative daily fasting blood glucose level was significantly lower in the MSP group than in the EDP group (6.3 ± 1.5 mmol/L vs 7.3 ± 1.5 mmol/L, P < 0.05). The rate of pancreatic fistula was higher in the MSP group than in the PD group (42% vs 20.5%, P = 0.039), all of the fistulas after MSP corresponded to grade A (9/15) or B (6/15) and were sealed following conservative treatment. There was no significant difference in the mean postoperative hospital stay between the MSP group and the other two groups. After a mean follow-up of 44 mo, no tumor recurrences were found, only one patient (2.8%) in the MSP group vs five (21.7%) in the EDP group developed new-onset insulin-dependent DM postoperatively (P = 0.029). Moreover, significantly fewer patients in the MSP group than in the PD (0% vs 33.3%, P < 0.001) and EDP (0% vs 21.7%, P = 0.007) required enzyme substitution. CONCLUSION MSP is a safe and organ-preserving option for benign or low-grade malignant lesions in the neck and proximal body of the pancreas.

Preparation and characterization of chitosan porous microcarriers for hepatocyte culture.

BACKGROUND The bioartificial liver (BAL) is considered a possible alternative method for treating liver failure. The core of the BAL system is culturing liver cells in vitro with high density and activity. Microcarrier culture is a mode of high-density culture. We set out to prepare a novel porous microcarrier to improve the activity of liver cells in vitro. METHODS Chitosan was used to prepare a novel porous spherical microcarrier with interconnected structure. The chitosan porous microcarriers (CPMs) were modified with gelatin to improve their biocompatibility. CPMs were co-cultured with liver cells, HL-7702 (L-02), to evaluate their effect on cell culture. RESULTS The average size of the CPMs was about 400 μm in diameter and their apertures were less than 30 μm. The pores of the microcarrier were interconnected. After fixation by sodium tripolyphosphate, the structure of the first freeze-dried CPMs was stable. To further improve the biocompatibility, the surface of CPMs was modified with gelatin through chemical crosslinking (GM-CPMs). Comparing the proliferation curves of L-02 cells cultured on simple CPMs, GM-CPMs and tissue culture polystyrene (TCPS, a mode of planar cell culture), the proliferation rates were similar in the first 5 days and the cells proliferated until day 8 in culture with microcarriers. The OD value of liver cells cultured on GM-CPMs was 1.97-fold higher than that on TCPS culture at day 8. Levels of urea and albumin in supernatants of cells cultured on GM-CPMs increased steadily for 8 days, and were clearly higher than those of cells cultured on TCPS (P<0.05). CONCLUSIONS The novel CPMs were promising microcarriers for hepatocyte culture and the GM-CPM seemed better. Porous microcarrier culture was beneficial for hepatocyte function and activity.

Microencapsulated tumor assay: Evaluation of the nude mouse model of pancreatic cancer

AIM To establish a more stable and accurate nude mouse model of pancreatic cancer using cancer cell microencapsulation. METHODS The assay is based on microencapsulation technology, wherein human tumor cells are encapsulated in small microcapsules (approximately 420 μm in diameter) constructed of semipermeable membranes. We implemented two kinds of subcutaneous implantation models in nude mice using the injection of single tumor cells and encapsulated pancreatic tumor cells. The size of subcutaneously implanted tumors was observed on a weekly basis using two methods, and growth curves were generated from these data. The growth and metastasis of orthotopically injected single tumor cells and encapsulated pancreatic tumor cells were evaluated at four and eight weeks postimplantation by positron emission tomography-computed tomography scan and necropsy. The pancreatic tumor samples obtained from each method were then sent for pathological examination. We evaluated differences in the rates of tumor incidence and the presence of metastasis and variations in tumor volume and tumor weight in the cancer microcapsules vs single-cell suspensions. RESULTS Sequential in vitro observations of the microcapsules showed that the cancer cells in microcapsules proliferated well and formed spheroids at days 4 to 6. Further in vitro culture resulted in bursting of the membrane of the microcapsules and cells deviated outward and continued to grow in flasks. The optimum injection time was found to be 5 d after tumor encapsulation. In the subcutaneous implantation model, there were no significant differences in terms of tumor volume between the encapsulated pancreatic tumor cells and cells alone and rate of tumor incidence. There was a significant difference in the rate of successful implantation between the cancer cell microencapsulation group and the single tumor-cell suspension group (100% vs 71.43%, respectively, P = 0.0489) in the orthotropic implantation model. The former method displayed an obvious advantage in tumor mass (4th wk: 0.0461 ± 0.0399 vs 0.0313 ± 0.021, t = -0.81, P = 0.4379; 8th wk: 0.1284 ± 0.0284 vs 0.0943 ± 0.0571, t = -2.28, respectively, P = 0.0457) compared with the latter in the orthotopic implantation model. CONCLUSION Encapsulation of pancreatic tumor cells is a reliable method for establishing a pancreatic tumor animal model.

A preliminary study of Alginate, Heparin-Chitosan-Alginate and Heparin microencapsulated hepatocytes system.

BACKGROUND/AIMS The purpose of this work was to develop a new microcapsule and improve its physical properties, such as mechanical stability and permeability. Then we aimed to study its biological properties. METHODOLOGY Alginate, Heparin-Chitosan-Alginate, Heparin microcapsules (ALCAL) with good mechanical stability were made from the high voltage pulsing microcapsule shaping device with low-molecular-weight heparin sodium (LMWH), alginate (ALG) and chitosan (CS) by supramolecular lay-by-lay self-assembled technology. We tested their physical properties and microencapsulated hepatocytes by ALCAL to study their biological properties. RESULTS It was found that the microcapsules had the smooth surface and the porous structure with interconnected pores from microscopic observation. The permeability experiment of microcapsules using FITC-BSA and FITC-IgG showed that the microcapsule had the molecular mass cut-off of 68-150kDa. The hepatocytes encapsulated in ALCAL microcapsule rapidly aggregated on the core. The aggregated cells showed high albumin synthesis and glucose removal, which showed it had good metabolic function. CONCLUSIONS The current study revealed that ALCAL microcapsules might thus be a forefront for an alternative membrane to be investigated for cell encapsulation on the bioartifcial liver.

Preparation of three-dimensional macroporous chitosan-gelatin B microspheres and HepG2-cell culture.

Chitosan–gelatin B microspheres with an open, interconnected, highly macroporous (100–200 µm) structure were prepared via a three‐step protocol combining freeze‐drying with an electrostatic and ionic cross‐linking method. Saturated tripolyphosphate ethanol solution (85% ethanol) was chosen as the crosslinking agent to prevent destruction of the porous structure and to improve the biostability of the chitosan–gelatin B microspheres, with N‐(3‐dimethylaminopropyl)‐N′‐ethyl‐carbodiimide/N‐hydroxysuccinimide as a second crosslinking agent to react with gelatin A and fixed chitosan–gelatin B microspheres to attain improved biocompatibility. Water absorption of the three‐dimensional macroporous chitosan–gelatin B microspheres (3D‐P‐CGMs) was 12.84, with a porosity of 85.45%. In vitro lysozyme degradation after 1, 3, 5, 7, 10, 14, and 21 days showed improved biodegradation in the 3D‐P‐CGMs. The morphology of human hepatoma cell lines (HepG2 cells) cultured on the 3D‐P‐CGMs was spherical, unlike that of cells cultured under traditional two‐dimensional conditions. Scanning electron microscopy and paraffin sections were used to confirm the porous structure of the 3D‐P‐CGMs. HepG2 cells were able to migrate inside through the pore. Cell proliferation and levels of albumin and lactate dehydrogenase suggested that the 3D‐P‐CGMs could provide a larger specific surface area and an appropriate microenvironment for cell growth and survival. Hence, the 3D‐P‐CGMs are eminently suitable as macroporous scaffolds for cell cultures in tissue engineering and cell carrier studies. Copyright