The future of organ-oriented research and treatment

En bloc procurement of porcine abdominal multiple organ block for ex situ normothermic machine perfusion: a technique for avoiding initial cold preservation

Background

Normothermic machine perfusion (NMP) is a technique that maintains organs ex situ with normal metabolism, and organ function can be better preserved. The study of multiple-organ NMP is rarely reported. Multiple organ block (MOB) is a self-perfusing system for maintaining multiple organs ex situ, and porcine MOBs have been successfully preserved for 18 to 37 h. Due to the above context, we conceived to maintain abdominal multiple organ block (AMOB) ex situ utilizing NMP technology.

Methods

AMOBs were procured from Ba-Ma miniature pigs through en bloc procurement surgery. The process of cold preservation was eliminated between the procurement and machine perfusion, and a few minutes of warm ischemia emerged. Autologous whole blood was collected during procurement surgery as a perfusate component in the beginning.

Results

The median time of procurement surgery was approximately 220 min, and the median time of warm ischemia was 300 sec. Cases 1 and 2 suffered from repeated hypotension during the procurement surgery, and case 2 exhibited hemorrhage. After improved and optimized procurement processes, the vital signs of cases 3 to 5 remained stable during procurement. In the NMP phase, the flow increased slowly in cases 1 and 2 and did not remain stable even after continuous infusion of a high-dose vasodilator. The lactic acid level rapidly increased, and the levels of ALT and AST were obviously higher than those in cases 3 to 5. In contrast, the flow rate increased smoothly in cases 3 to 5. The lactic acid level remained stable during the first 10 h of perfusion.

Conclusions

AMOB procurement from heart-beating pigs for NMP without initial cold preservation is technically feasible.

Modular assembly-based approach of loosely packing co-cultured hepatic tissue elements with endothelialization for liver tissue engineering

Background

In liver tissue engineering, co-culturing hepatocytes with typical non-parenchymal hepatic cells to form cell aggregates is available to mimic the in vivo microenvironment and promote cell biological functions. With a modular assembly approach, endothelialized hepatic cell aggregates can be packed for perfusion culture, which enables the construction of large-scale liver tissues. Since tightly packed aggregates tend to fuse with each other and block perfusion flows, a loosely packed mode was introduced in our study.

Methods

Using an oxygen-permeable polydimethylsiloxane (PDMS)-based microwell device, highly dense endothelialized hepatic cell aggregates were generated as hepatic tissue elements by co-culturing hepatocellular carcinoma (HepG2) cells, Swiss 3T3 cells, and human umbilical vein endothelial cells (HUVECs). The co-cultured aggregates were then harvested and applied in a PDMS-fabricated bioreactor for 10 days of perfusion culture. To maintain appropriate interstitial spaces for stable perfusion, biodegradable poly-L-lactic acid (PLLA) scaffold fibers were used and mixed with the aggregates, forming a loosely packed mode.

Results

In a microwell co-culture, Swiss 3T3 cells significantly contributed to the formation of hepatic cell aggregates. HUVECs developed a peripheral distribution in aggregates for endothelialization. In the perfusion culture, compared with pure HepG2 aggregates, HepG2/Swiss 3T3/HUVECs co-cultured aggregates exhibited a higher level of cell proliferation and liver-specific function expression (i.e., glucose consumption and albumin secretion). Under the loosely packed mode, co-cultured aggregates showed a characteristic histological morphology with cell migration and adhesion to fibers. The assembled hepatic tissue elements were obtained with 32% of in vivo cell density.

Conclusions

In a co-culture of HepG2, Swiss 3T3, and HUVECs, Swiss 3T3 cells were observed to be beneficial for the formation of endothelialized hepatic cell aggregates. Loosely packed aggregates enabled long-term perfusion culture with high viability and biological function. This study will guide us in constructing large-scale liver tissue models by way of aggregate-based modular assembly.

A new platform for laparoscopic training: initial evaluation of the ex-vivo live multivisceral training device

BACKGROUND

Various training models have been developed for laparoscopic training. Inanimate models including cadavers, ex-vivo simulator, and virtual reality (VR), are less realistic and often fail to display specific events such as bleeding, bile leakage, etc. Animal models provide more realistic experience, but constraints like cost involved, anesthetic requirement, and ethical approval have limited its application. We have designed a new training ex-vivo simulator-Smagister to address these issues.

METHODS

The Smagister consists of a normothermic machine perfusion platform, multivisceral organ of porcine abdominal cavity (liver, gallbladder, pancreas, stomach, intestine, kidney, uterus, bladders, etc.), high-definition display, and software system. Blood gas analysis and number of peristalsis per hour were recorded. A questionnaire was used to subjectively assess vitality of the organ cluster every hour. Three laparoscopic procedures including cholecystectomy (LC), enterotomy closure (LEC) and hepatectomy (LLR) were performed on Smagister, with demonstration of specific events for each procedure. Six experts compared the procedures with actual surgery in terms of feasibility to complete procedures and demonstration of complications.

RESULTS

The fluctuation of perfusate glucose (6.1-8.2 mmol/L) and lactate (5.82-6.55 mmol/L) suggested metabolic function of the multivisceral organs. The mean number of peristalsis was 2.2/min. The simulated surgical view and anatomic structures closely resembled actual surgery during continuous perfusion (3.5 ± 1.0, 3.8 ± 0.8, respectively). The evaluation scores of haptic feedbacks were 3.8 ± 0.8, resembling live tissue handling. LC, LEC, and LLR were performed well on the Smagister, with clear display of the specific events. All six experts considered Smagister as a suitable training modality for both basic and advanced laparoscopic surgery.

CONCLUSION

The amalgamation of live animal model and ex-vivo simulation in Smagister centralizes the virtue of both modalities, expands the training field, and provides high-fidelity laparoscopic training for both novice and senior surgeons.