Heparin-gelatin mixture improves vascular reconstruction efficiency and hepatic function in bioengineered livers

Perfusion retains the inherent vascular network (portal vein, hepatic artery, and hepatic veins), necessary for the transportation of nutrients and oxygen within liver during recellularization and post-transplantation in vivo.

“Moreover, perfusion retains the inherent vascular network (portal vein, hepatic artery, and hepatic veins), necessary for the transportation of nutrients and oxygen within liver during the recellularization process and post-transplantation in vivo [13,14,168].”

HepG2 cells exhibit higher expression of functional genes, including albumin, LDLR, and CYP2E1, as well as increased albumin secretion when cultured following efficient reendothelization and coating of the vascular tree with a heparin-gelatin mixture compared to uncoated reendothelized porcine liver.

“HepG2 cells exhibit higher expression of functional genes, including albumin, low-density lipoprotein receptor (LDLR), and CYP2E1, as well as increased albumin secretion when cultured following efficient reendothelization and coating of the vascular tree with a heparin-gelatin mixture compared to uncoated reendothelized porcine liver [14].”

Several studies have been conducted to evaluate the feasibility of recellularizing decellularized livers, primarily on rodent liver initially, and researchers have continued to scale it up using whole porcine and human livers.

“Several studies have been conducted to evaluate the feasibility of recellularizing decellularized livers, primarily on rodent liver initially, and researchers have continued to scale it up using whole porcine and human livers (Table 1) [8,14,101,110,[193], [194], [195]].”

HepG2 cells efficiently repopulate decellularized rat, porcine, and human livers while retaining their function and proliferative capacity.

“HepG2 cells efficiently repopulate decellularized rat, porcine, and human livers while retaining their function and proliferative capacity [14,15,204].”

Efficient reendothelization is important in protecting parenchymal cells from shear stress caused by media perfusion and enhancing hepatocyte function.

“This emphasizes the importance of efficient reendothelization in protecting parenchymal cells from shear stress caused by media perfusion and enhancing hepatocyte function.”

Reconstruction of the vascular network becomes necessary to allow the perfusion of the graft with host blood, ensuring the supply of nutrients and oxygen to different regions of the bioengineered organ.

“Therefore, reconstruction of the vascular network becomes necessary to allow the perfusion of the graft with host blood, ensuring the supply of nutrients and oxygen to different regions of the bioengineered organ [14,222].”

Combining heparin and gelatin as a mixture creates a sticky surface on blood vessel surfaces and improves reendothelialization efficiency in decellularized porcine liver.

“Hussein et al. combined both heparin and gelatin as a mixture to create a sticky surface on blood vessel surfaces, improving reendothelialization efficiency in decellularized porcine liver (Fig. 4) [14].”

Coculturing HepG2 cells and endothelial cells in decellularized liver and transplanting it heterotopically into pigs resulted in no obvious thrombosis and better hepatocyte function compared to uncoated liver scaffolds.

“Moreover, they cocultured HepG2 cells and endothelial cells in the decellularized liver and transplanted it heterotopically into pigs, observing no obvious thrombosis and better hepatocyte function compared to uncoated liver scaffolds.”

Livers reendothelialized using EA. hy926 ECs in dynamic bioreactor culture for 10 days showed no clots after ex vivo blood perfusion for 24 h.

“Livers reendothelialized using EA. hy926 ECs in a dynamic culture in a bioreactor for 10 days showed no clots after ex vivo blood perfusion for 24 h.”

HUVECs and EA. hy926 cells have been extensively used for reendothelization of decellularized livers due to relative ease of accessibility, non-invasive harvesting from medical waste, and high yield following isolation.

“Cell lines, including HUVECs and EA. hy926 cells, have been extensively used for reendothelization of decellularized livers due to their relative ease of accessibility and the non-invasive harvesting from medical waste, in addition to a high yield following isolation [10,13,14,235].”

Both HUVECs and EA. hy926 cells were able to line the blood vessels of decellularized livers, with a significant reduction in platelet adhesion and clot formation during ex vivo blood perfusion, and demonstrated the ability to withstand blood flow after in vivo transplantation in pigs.

“Both cell types were able to line the blood vessels of decellularized livers, with a significant reduction in platelet adhesion and clot formation during ex vivo blood perfusion and demonstrated the ability to withstand blood flow after in vivo transplantation in pigs.”

In a pig, heterotopic transplantation of a heparin-gelatin precoated decellularized porcine right lateral lobe reendothelialized with EA. hy926 and reseeded with HepG2 cells for 1 h showed patency of the vascular tree upon contrast radiography, down-regulated coagulation markers, and higher expression of hepatic liver function compared to controls.

“They transplanted the bioengineered lobe heterotopically in a pig for 1 h and reported that the patency of the vascular tree upon contrast radiography with down-regulated expression of the coagulation markers and a higher expression of the hepatic liver function in heparin-gelatin precoated liver scaffolds.”