Pre-coating decellularized liver with HepG2-conditioned medium improves hepatic recellularization

The journey of decellularized vessel: from laboratory to operating room

Over the past few decades, there has been a remarkable advancement in the field of transplantation. But the shortage of donors is still an urgent problem that requires immediate attention. As with xenotransplantation, bioengineered organs are promising solutions to the current shortage situation. And decellularization is a unique technology in organ-bioengineering. However, at present, there is no unified decellularization method for different tissues, and there is no gold-standard for evaluating decellularization efficiency. Meanwhile, recellularization, re-endothelialization and modification are needed to form transplantable organs. With this mind, we can start with decellularization and re-endothelialization or modification of small blood vessels, which would serve to address the shortage of small-diameter vessels while simultaneously gathering the requisite data and inspiration for further recellularization of the whole organ-scale vascular network. In this review, we collect the related experiments of decellularization and post-decellularization approaches of small vessels in recent years. Subsequently, we summarize the experience in relation to the decellularization and post-decellularization combinations, and put forward obstacle we face and possible solutions.

iPSC-derived cells for whole liver bioengineering

Liver bioengineering stands as a prominent alternative to conventional hepatic transplantation. Through liver decellularization and/or bioprinting, researchers can generate acellular scaffolds to overcome immune rejection, genetic manipulation, and ethical concerns that often accompany traditional transplantation methods, in vivo regeneration, and xenotransplantation. Hepatic cell lines derived from induced pluripotent stem cells (iPSCs) can repopulate decellularized and bioprinted scaffolds, producing an increasingly functional organ potentially suitable for autologous use. In this mini-review, we overview recent advancements in vitro hepatocyte differentiation protocols, shedding light on their pivotal role in liver recellularization and bioprinting, thereby offering a novel source for hepatic transplantation. Finally, we identify future directions for liver bioengineering research that may allow the implementation of these systems for diverse applications, including drug screening and liver disease modeling.

Crosslinked modified decellularized rabbit conjunctival stroma for reconstruction of tissue-engineered conjunctivain vitro

Conjunctival reconstruction is an essential part of ocular surface restoration, especially in severe conjunctival disorders. Decellularized conjunctival tissues have been used in tissue engineering. In this study, we investigated the feasibility of constructing tissue-engineered conjunctiva using stem cell (human amniotic epithelial cells, hAECs), and cross-linked modified decellularized rabbit conjunctival stroma (DRCS-Asp-hEGF), and decellularized rabbit conjunctiva stroma (DRCS). With phospholipase A2 and sodium dodecyl, DRCS were nearly DNA-free, structurally intact and showed no cytotoxic effectsin vitro, as confirmed by DNA quantification, histology, and immunofluorescence. The results of Fourier transform infrared, Alcian blue staining and human epidermal growth factor (hEGF) release assays showed that DRCS-Asp-hEGF was successfully prepared via crosslinking with aspartic acid (Asp) and modified by hEGF at pH 7.7. The hAECs were positive for octamer-binding transcription factor-4 and ABCG2 cell markers. The hAECs were directly placed on the DRCS and DRCS-Asp-hEGF for five days respectively. Tissue-engineered conjunctiva was constructedin vitrofor five days, and the fluorescence staining results showed that hAECs grew in monolayers on DRCS-Asp-hEGF and DRCS. Flow cytometry results showed that compared with DRCS, the number of apoptotic cells stained in DRCS-Asp-hEGF was small, 86.70 ± 0.79% of the cells survived, and 87.59 ± 1.43% of the cells were in the G1 phase of DNA synthesis. Electron microscopy results showed that desmosome junction structures, which were similar to the native conjunctival tissue, were formed between cells and the matrix in the DRCS-Asp-hEGF.

Self-Calibrating Lanthanide Infinite Coordination Polymer Constructs Fluorescent Probes: A Sensitive Approach for Early Diagnosis of Hepatocellular Carcinoma and Environmental Analysis

The development of a self-calibrating ratio fluorescence probe without the need for additional substrates is a major advancement in biosensing. In this study, at room temperature, a self-calibrating infinite coordination polymer (SSA-Tb-ATP ICPs) has been proposed by self-assembling adenosine triphosphate (ATP) with 5-sulfosalicylic acid (SSA) and Tb3+. Due to the antenna effect, SSA-Tb-ATP ICPs exhibited strong green fluorescence emission of Tb3+ (at 547 nm) and blue fluorescence emission of SSA (at 407 nm). This material offers several advantages over existing detection methods, including simplicity of synthesis and exceptional sensitivity. Our self-calibrating SSA-Tb-ATP ICPs demonstrated excellent performance in detecting alkaline phosphatase (ALP) and phosphate (Pi) in both serum and environmental samples with detection limits of 0.076 U/L and 0.025 μM, respectively. Moreover, we successfully employed the SSA-Tb-ATP ICPs to perform cellular imaging of ALP in both hepatocellular carcinoma cells (HepG2) and normal liver cells (LO2), representing a significant advancement in ALP detection and imaging. The simplicity of the synthesis and high sensitivity make this probe a promising tool for early diagnosis of hepatocellular carcinoma in clinical settings and environment analysis.

Decellularization Techniques for Tissue Engineering: Towards Replicating Native Extracellular Matrix Architecture in Liver Regeneration

The process of tissue regeneration requires the utilization of a scaffold, which serves as a structural framework facilitating cellular adhesion, proliferation, and migration within a physical environment. The primary aim of scaffolds in tissue engineering is to mimic the structural and functional properties of the extracellular matrix (ECM) in the target tissue. The construction of scaffolds that accurately mimic the architecture of the extracellular matrix (ECM) is a challenging task, primarily due to the intricate structural nature and complex composition of the ECM. The technique of decellularization has gained significant attention in the field of tissue regeneration because of its ability to produce natural scaffolds by removing cellular and genetic components from the extracellular matrix (ECM) while preserving its structural integrity. The present study aims to investigate the various decellularization techniques employed for the purpose of isolating the extracellular matrix (ECM) from its native tissue. Additionally, a comprehensive comparison of these methods will be presented, highlighting their respective advantages and disadvantages. The primary objective of this study is to gain a comprehensive understanding of the anatomical and functional features of the native liver, as well as the prevalence and impact of liver diseases. Additionally, this study aims to identify the limitations and difficulties associated with existing therapeutic methods for liver diseases. Furthermore, the study explores the potential of tissue engineering techniques in addressing these challenges and enhancing liver performance. By investigating these aspects, this research field aims to contribute to the advancement of liver disease treatment and management.

Decellularized Extracellular Matrix: The Role of This Complex Biomaterial in Regeneration

Organ transplantation is understood as a technique where an organ from a donor patient is transferred to a recipient patient. This practice gained strength in the 20th century and ensured advances in areas of knowledge such as immunology and tissue engineering. The main problems that comprise the practice of transplants involve the demand for viable organs and immunological aspects related to organ rejection. In this review, we address advances in tissue engineering for reversing the current challenges of transplants, focusing on the possible use of decellularized tissues in tissue engineering. We address the interaction of acellular tissues with immune cells, especially macrophages and stem cells, due to their potential use in regenerative medicine. Our goal is to exhibit data that demonstrate the use of decellularized tissues as alternative biomaterials that can be applied clinically as partial or complete organ substitutes.

Recent advancement of decellularization extracellular matrix for tissue engineering and biomedical application

BACKGROUND

Decellularized extracellular matrixs (dECMs) derived from organs and tissues have emerged as a promising tool, as they encompass the characteristics of an ideal tissue scaffold: complex composition, vascular networks and unique tissue-specific architecture. Consequently, their use has propagated throughout tissue engineering and regenerative medicine. dECM can be easily obtained from various tissues/organs by appropriate decellularization protocolsand is entitled to provide necessary cues to cells homing.

METHODS

In this review, we describe the decellularization and sterilization methods that are commonly used in recent research, the effects of these methods upon biologic scaffold material are discussed. Also, we summarize the recent developments of recellularization and vascularization techniques in regeneration medicine. Additionally, dECM preservation methods is mentioned, which provides the basis for the establishment of organ bank.

RESULTS

Biomedical applications and the status of current research developments relating to dECM biomaterials are outlined, including transplantation in vivo, disease models and drug screening, organoid, 3D bioprinting, tissue reconstruction and rehabilitation and cell transplantation and culture. Finally, critical challenges and future developing technologies are discussed.

CONCLUSIONS

With the development of tissue engineering and regenerative medicine, dECM will have broader applications in the field of biomedicine in the near future.

Natural Scaffolds Used for Liver Regeneration: A Narrative Update

Annually chronic liver diseases cause two million death worldwide. Although liver transplantation (LT) is still considered the best therapeutic option, the limited number of donated livers and lifelong side effects of LT has led researchers to seek alternative therapies. Tissue engineering (TE) as a promising method is considered for liver repair and regeneration. TE uses natural or synthetic scaffolds, functional somatic cells, multipotent stem cells, and growth factors to develop new organs. Biological scaffolds are notable in TE because of their capacity to mimic extracellular matrices, biodegradability, and biocompatibility. Moreover, natural scaffolds are classified based on their source and function in three separate groups. Hemostat-based scaffolds as the first group were reviewed for their application in coagulation in liver injury or surgery. Furthermore, recent studies showed improvement in the function of biological hydrogels in liver regeneration and vascularity. In addition, different applications of natural scaffolds were discussed and compared with synthetic scaffolds. Finally, we focused on the efforts to improve the performance of decellularized extracellular matrixes for liver implantation.

A new strategy for the decellularization of whole organs by hydrostatic pressure

Tissue engineering has been able to develop novel decellularization-recellularization techniques, which facilitates the research for the generation of functional organs. This is based in the initial obtention of the organ's extracellular matrix (ECM). Therefore, any improvement in the decellularization process would have a positive impact in the results of the recellularization process. Nevertheless, commonly the methods and equipment employed for this process are expensive and thus limit the access of this technique to various research groups globally.

AIM

To develop a decellularization technique with the exclusive use of hydrostatic pressure of detergent solutions, to have an easily accessible and low-cost technique that meets the basic requirements of acellularity and functionality of the ECM.

METHODS

This experimental study was performed in 10 male Wistar rats, obtaining the liver to carry out serial washes, with 1, 2 and 3% Triton X-100 solutions and 0.1% SDS. The washes were performed by using a Gravity Perfusion System (GPS), which assured us a continuous hydrostatic pressure of 7.5 mmHg. The obtained ECM was processed using stains and immunostaining to determine the residual cell content and preservation of its components.

RESULTS

The staining showed a removal of cellular and nuclear components of approximately 97% of the acellular ECM, with an adequate three-dimensional pattern of collagen and proteoglycans. Furthermore, the acellular ECM allowed the viability of a primary hepatocyte culture.

CONCLUSIONS

The use of the GPS decellularization technique allowed us to obtain an acellular and functional ECM, drastically reducing experimentation costs. This article is protected by copyright. All rights reserved.

Application of triple co-cultured cell spheroid model for exploring hepatotoxicity and metabolic pathway of AFB1

The toxicity evaluation suffers from the absence of suitable models capable of replicating in the co-cultured cell microenvironment and the function of specific tissues in vitro. Motivated by this urgent need, this study aimed to describe a novel three-dimensional (3D) liver spheroid model. The model consisted of a triple co-culture of HepG2, EA.hy 926, and LX-2. Subsequently, it was used for the toxicity evaluation of aflatoxin B1 (AFB1), and its advantages over the two-dimensional (2D) model and the mono-type cell spheroid model were assessed. This study examined the effects of AFB1 on cell viability, proliferation, mitochondria, oxidative stress, and cell membranes. The results revealed that AFB1 greatly affected 2D cell membranes and oxidative stress levels (0.01 μg/mL; 24 h), and could also significantly affect 2D cell viability, proliferation, and mitochondria levels (1 μg/mL; 24 h). On the contrary, 3D cells were less susceptible to AFB1. Combined with the analysis of gene expression, both metabolic activation (cytochrome P450; CYP450) and detoxification efficiency (drug-metabolizing enzymes) were found to be higher in 3D cells than in 2D cells. Moreover, 3D cells in triple co-culture outperformed mono-type cell spheroids. Therefore, the advanced 3D co-cultured spheroid model constructed in this study allowed us to more realistically simulate the microenvironment in vitro, and was a valuable and precise model to study mycotoxins.

Recent Advances in Liver Engineering With Decellularized Scaffold

Liver transplantation is currently the only effective treatment for patients with end-stage liver disease; however, donor liver scarcity is a notable concern. As a result, extensive endeavors have been made to diversify the source of donor livers. For example, the use of a decellularized scaffold in liver engineering has gained considerable attention in recent years. The decellularized scaffold preserves the original orchestral structure and bioactive chemicals of the liver, and has the potential to create a de novo liver that is fit for transplantation after recellularization. The structure of the liver and hepatic extracellular matrix, decellularization, recellularization, and recent developments are discussed in this review. Additionally, the criteria for assessment and major obstacles in using a decellularized scaffold are covered in detail.

In-vitro and in-vivo hemostat evaluation of decellularized liver extra cellular matrix loaded chitosan/gelatin spongy scaffolds for liver injury

Individually, Chitosan (C) and Gelatin (G) are increasingly being used for the simulation and testing of surgical procedures. In the present study, at combination of chitosan/gelatin (CG) was optimized and later enriched by the loading decellularized liver extracellular matrix powder (dLECM) prepared from porcine liver, we hypothesized CG-dLECM combination would enhance wound healing and reduce postoperative complications after liver surgery. Varying concentration of dLECM (1, 4, and 8 mg/ml) were loaded into CG, and evaluation was done to get the optimized composition. Preliminary analysis on the microstructure, in-vitro degradation, and blood clot kinetics and in-vitro cytocompatibility showed that the CG with 4 mg/ml dLECM (CG-E4) was the most suitable composition for further consideration. The prepared CG-E4 spongy scaffold enhances fast post-operative recovery with a higher blood absorption and fast clotting time (~50 s). In addition, CG-E4 spongy scaffold implanted at rat liver wound showed desired biocompatibility as evidenced by reduced wound size, earlier bioabsorption and accelerated liver regeneration. In the present study, we demonstrated that, CG with dLECM spongy scaffold as a potential hemostatic material in the prevention of excessive hemorrhage during surgeries.

Applications of Biomaterials in 3D Cell Culture and Contributions of 3D Cell Culture to Drug Development and Basic Biomedical Research

The process of evaluating the efficacy and toxicity of drugs is important in the production of new drugs to treat diseases. Testing in humans is the most accurate method, but there are technical and ethical limitations. To overcome these limitations, various models have been developed in which responses to various external stimuli can be observed to help guide future trials. In particular, three-dimensional (3D) cell culture has a great advantage in simulating the physical and biological functions of tissues in the human body. This article reviews the biomaterials currently used to improve cellular functions in 3D culture and the contributions of 3D culture to cancer research, stem cell culture and drug and toxicity screening.