The viability and function of primary rat hepatocytes cultured on polymeric membranes developed for hybrid artificial liver devices

Stem cells in liver failure

Orthotopic liver transplantation (OLT) represents the only reliable therapeutic approach for acute liver failure (ALF), liver failure associated to end-stage chronic liver diseases (CLD) and non-metastatic liver cancer. The clinical impact of liver failure is relevant because of the still high ALF mortality and the increasing worldwide prevalence of cirrhosis that, in turn, is the main predisposing cause for hepatocellular carcinoma (HCC). Moreover, in the next decade because an increased number of patients reaching end-stage disease and requiring OLT may face a shortage of donor livers. This clinical scenario led several laboratories to explore the feasibility and efficiency of alternative approaches, involving cellular therapy, to counteract liver failure. The present chapter overviews results and concepts emerged from recent experimental and clinical studies in which adult or embryonic hepatocytes, hepatic stem/progenitor cells, induced pluripotent stem (iPS) cells as well as extrahepatic stem cells have been used as putative transplantable cell sources.

Therapeutic application of stem cells in gastroenterology: An up-date

Adult stem cells represent the self-renewing progenitors of numerous body tissues, and they are currently classified according to their origin and differentiation ability. In recent years, the research on stem cells has expanded enormously and holds therapeutic promises for many patients suffering from currently disabling diseases. This paper focuses on the possible use of stem cells in the two main clinical settings in gastroenterology, i.e., hepatic and intestinal diseases, which have a strong impact on public health worldwide. Despite encouraging results obtained in both regenerative medicine and immune-mediated conditions, further studies are needed to fully understand the biology of stem cells and carefully assess their putative oncogenic properties. Moreover, the research on stem cells arouses fervent ethical, social and political debate. The Italian Society of Gastroenterology sponsored a workshop on stem cells held in Verona during the XVI Congress of the Federation of Italian Societies of Digestive Diseases (March 6-9, 2010). Here, we report on the issues discussed, including liver and intestinal diseases that may benefit from stem cell therapy, the biology of hepatic and intestinal tissue repair, and stem cell usage in clinical trials.

Morphological and functional behaviors of rat hepatocytes cultured on single-walled carbon nanotubes

This study describes the morphological and functional behaviors of rat hepatocytes on single-walled carbon nanotube (CNT)-coated surfaces. Although the hydrophobic characteristics of CNT-coated surfaces increased with increasing CNT density, hepatocyte adhesion decreased, indicating that the interaction between hepatocytes and CNTs is weak. We found that hepatocytes on a CNT-coated surface gradually gather together and form spheroids (spherical multicellular aggregates). These spheroids exhibit compact spherical morphology with a smooth surface and express connexin-32, an intracellular communication molecule. In contrast, collagen treatment in conjunction with the CNT-coated surface improved hepatocyte adhesion, and the cells maintained a monolayer configuration throughout the culture period. The albumin secretion and ammonia removal activities of hepatocyte spheroids were maintained at elevated levels for at least 15 days of culturing as compared with hepatocyte monolayers. These results indicate that CNTs can be used for the formation and long-term culture of hepatocyte spheroids.

Stem and progenitor cells in liver regeneration and repair

Mammalian liver has a unique capacity to regenerate following resection or injury, and recovery of liver mass is mainly through proliferation of remaining adult hepatocytes. However, in pathologic conditions, especially during acute liver failure (ALF) and advanced stages of chronic liver disease (CLD), regeneration eventually fails and orthothopic liver transplantation (OLT) represents the only curative approach. The clinical scenario of a world-wide increasing incidence of end-stage CLD and an associated lack of organ availability has led several laboratories to explore the feasibility and efficiency of experimental alternatives to OLT involving cellular therapy. This review presents experimental and clinical studies performed in the last 10-15 years where adult and embryonic hepatocytes, hepatic stem/progenitor cells and extrahepatic stem cells have been used as transplantable cell sources.

Morphological and functional studies of rat hepatocytes on a hydrophobic or hydrophilic polydimethylsiloxane surface

This study describes the morphological and functional behavior of rat hepatocytes on a polydimethylsiloxane (PDMS)-coated surface. Hepatocytes were cultured on hydrophobic or hydrophilic PDMS-coated surfaces in serum-free and serum-containing media. In the serum-free medium, almost all hepatocytes adhered onto the surface irrespective of the wettability, with a cell adhesion ratio of >90% at 24h. In the serum-containing medium, although they strongly adhered onto the hydrophilic surface (cell adhesion ratio >85%), the ratio on the hydrophobic surface was <15%. Furthermore, hepatocytes in the serum-free medium gradually formed spheroids irrespective of the surface characteristics; however, on the hydrophilic surface in the serum-containing medium, they maintained a monolayer configuration for up to 10 days, and their numbers gradually decreased over time. Expression levels of the functional activities (albumin secretion and ammonia removal) and the cell-cell adhesion molecules (cadherin and connexin-32) were higher in the hepatocytes that formed spheroids compared to those which assumed a monolayer configuration, and these levels were maintained for at least 10 days. These results suggest that the wettability of PDMS and the composition of the culture medium together control the cell adhesion, morphology and expression of functional genes in hepatocytes.

The compatibility of hepatocytes with chemically modified porous silicon with reference to in vitro biosensors

Porous Si is a nanostructured material that is of interest for molecular and cell-based biosensing, drug delivery, and tissue engineering applications. Surface chemistry is an important factor determining the stability of porous Si in aqueous media, its affinity for various biomolecular species, and its compatibility with tissues. In this study, the attachment and viability of a primary cell type to porous Si samples containing various surface chemistries is reported, and the ability of the porous Si films to retain their optical reflectivity properties relevant to molecular biosensing is assessed. Four chemical species grafted to the porous Si surface are studied: silicon oxide (via ozone oxidation), dodecyl (via hydrosilylation with dodecene), undecanoic acid (via hydrosilylation with undecylenic acid), and oligo(ethylene) glycol (via hydrosilylation with undecylenic acid followed by an oligo(ethylene) glycol coupling reaction). Fourier Transform Infrared (FTIR) spectroscopy and contact angle measurements are used to characterize the surface. Adhesion and short-term viability of primary rat hepatocytes on these surfaces, with and without pre-adsorption of collagen type I, are assessed using vital dyes (calcein-AM and ethidium homodimer I). Cell viability on undecanoic acid-terminated porous Si, oxide-terminated porous Si, and oxide-terminated flat (non-porous) Si are monitored by quantification of albumin production over the course of 8 days. The stability of porous Si thin films after 8 days in cell culture is probed by measuring the optical interferometric reflectance spectra. Results show that hepatocytes adhere better to surfaces coated with collagen, and that chemical modification does not exert a deleterious effect on primary rat hepatocytes. The hydrosilylation chemistry greatly improves the stability of porous Si in contact with cultured primary cells while allowing cell coverage levels comparable to standard culture preparations on tissue culture polystyrene.

Research progress and prospects of bioartificial liver system

Liver transplantation is the only established treatment for acute liver failure (ALF), one of the most challenging clinical syndromes; however, donor shortages remain problematic. Artificial livers as a bridge to liver transplantation are being considered worldwide. Non-bioarticifical liver (NBAL) have limitations in improving the survival rates. Therefore, a biological artificial liver (BAL) that has metabolic, detoxic,and synthetic function of hepatocytes is anticipated. Biological artificial livers are classified by cell source, types of culture system for hepatocytes, and types of bioreactor. This paper reviews the bioartificial liver devices that have been clinically tested to support ALF patients. Finally, we identify several improvements critical to bioartificial liver replacement therapy in the future.

Tissue engineering and organ structure: a vascularized approach to liver and lung

Over the past two decades, great strides have been made in the field of tissue engineering. Many of the initial attempts to develop an engineered tissue construct were based on the concept of seeding cells onto an avascular scaffold. Using advanced manufacturing technologies, the creation of a preformed vascular scaffold has become a reality. This article discusses some of the issues surrounding the development of such a vascular scaffold. We then examine of the challenges associated with applying this scaffold technology to two vital organ constructs: liver and lung.