Development of a Cell-Based Biosensor for Residual Detergent Detection in Decellularized Scaffolds

Real-Time, Non-Invasive Monitoring of Neuronal Differentiation Using Intein-Enabled Fluorescence Signal Translocation in Genetically Encoded Stem Cell-Based Biosensors

Real-time and non-invasive monitoring of neuronal differentiation will help increase our understanding of neuronal development and help develop regenerative stem cell therapies for neurodegenerative diseases. Traditionally, reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunofluorescence (IF) staining have been widely used to investigate stem cell differentiation; however, their limitations include endpoint analysis, invasive nature of monitoring, and lack of single-cell-level resolution. Several limitations hamper current approaches to studying neural stem cell (NSC) differentiation. In particular, fixation and staining procedures can introduce artificial changes in cellular morphology, hindering our ability to accurately monitor the progression of the process and fully understand its functional aspects, particularly those related to cellular connectivity and neural network formation. Herein, we report a novel approach to monitor neuronal differentiation of NSCs non-invasively in real-time using cell-based biosensors (CBBs). Our research efforts focused on utilizing intein-mediated protein engineering to design and construct a highly sensitive biosensor capable of detecting a biomarker of neuronal differentiation, hippocalcin. Hippocalcin is a critical protein involved in neurogenesis, and the CBB functions by translocating a fluorescence signal to report the presence of hippocalcin externally. To construct the hippocalcin sensor proteins, hippocalcin bioreceptors, AP2 and glutamate ionotropic receptor AMPA-type subunit 2 (GRIA2), were fused to each split-intein carrying split-nuclear localization signal (NLS) peptides, respectively, and a fluorescent protein was introduced as a reporter. Protein splicing (PS) was triggered in the presence of hippocalcin to generate functional signal peptides, which promptly translocated the fluorescence signal to the nucleus. The stem cell-based biosensor showed fluorescence signal translocation only upon neuronal differentiation. Undifferentiated stem cells or cells that had differentiated into astrocytes or oligodendrocytes did not show fluorescence signal translocation. The number of differentiated neurons was consistent with that measured by conventional IF staining. Furthermore, this approach allowed for the monitoring of neuronal differentiation at an earlier stage than that detected using conventional approaches, and the translocation of fluorescence signal was monitored before the noticeable expression of class III β-tubulin (TuJ1), an early neuronal differentiation marker. We believe that these novel CBBs offer an alternative to current techniques by capturing the dynamics of differentiation progress at the single-cell level and by providing a tool to evaluate how NSCs efficiently differentiate into specific cell types, particularly neurons.

The trend of allogeneic tendon decellularization: literature review

Tendon injuries repair is a significant burden for orthopaedic surgeons. Finding a proper graft material to repair tendon is one of the main challenges in orthopaedics, for which the requirement of substitute for tendon repair would be different for each clinical application. Among biological scaffolds, the use of decellularized tendon increasingly represents an interesting approach to treat tendon injuries and several articles have investigated the approaches of tendon decellularization. To understand the outcomes of the the approaches of tendon decellularization on effect of tendon transplantation, a literature review was performed. This review was conducted by searching in Pubmed and Embase and 64 studies were included in this study. The findings revealed that the common approaches to decellularize tendon include chemical, physical, and enzymatic decellularization methods or their combination. With the development of tissue engineering, researchers also put forward new theories such as automatic acellular machine, 3D printing technology to manufacture acellular scaffold.

Optimizing Decellularization of Bovine Ovarian Tissue: Toward a Transplantable Artificial Ovary Scaffold with Minimized Residual Toxicity and Preserved Extracellular Matrix Morphology

INTRODUCTION

The decellularized extracellular matrix (dECM) from ovarian tissue could be the best scaffold for the development of a transplantable artificial ovary. Typically, dECM from ovarian tissue has been obtained using sodium dodecyl sulfate (SDS), at a concentration of 1% for 24 h. However, SDS can leave residues in the tissue, which may be toxic to the seeded cells. This study aimed to obtain dECM from bovine ovarian tissue using SDS and NaOH at a minimum concentration in the shortest incubation time.

METHODS

The respective SDS and NaOH concentrations investigated were 1% and 0.2 m; 0.5% and 0.1 m; 0.1% and 0.02 m; and 0.05% and 0.01 m, with 24-, 12-, and 6-h incubation periods. After the incubation time, the tissue was washed in 50 mL of distilled water for 6 h.

RESULTS

Histological analysis confirmed decellularization and showed the conservation of collagen fibers in all samples following treatment. Furthermore, the lowest SDS and NaOH concentrations that showed no DNA remaining during electrophoresis analysis were 0.1% and 0.02 m when incubated for 24 and 12 h. DNA quantification resulted in <0.2 ng DNA/mg ovarian tissue using these protocols. Additionally, the coculture of dECM (obtained by 0.1% SDS and 0.02 m NaOH for 12 h) with ovarian cells showed that there was no toxic effect for the cells for up to 72 h.

CONCLUSION

The protocol involving 0.1% SDS and 0.02 m NaOH for 12-h incubation decellularizes bovine ovarian tissue, generating a dECM that preserves the native ECM morphology and is nontoxic to ovarian cells.

Plumping up a Cushion of Human Biowaste in Regenerative Medicine: Novel Insights into a State-of-the-Art Reserve Arsenal

Major breakthroughs and disruptive methods in disease treatment today owe their thanks to our inch by inch developing conception of the infinitive aspects of medicine since the very beginning, among which, the role of the regenerative medicine can on no account be denied, a branch of medicine dedicated to either repairing or replacing the injured or diseased cells, organs, and tissues. A novel means to accomplish such a quest is what is being called "medical biowaste", a large assortment of biological samples produced during a surgery session or as a result of physiological conditions and biological activities. The current paper accentuating several of a number of promising sources of biowaste together with their plausible applications in routine clinical practices and the confronting challenges aims at inspiring research on the existing gap between clinical and basic science to further extend our knowledge and understanding concerning the potential applications of medical biowaste.

Mimicking the Natural Basement Membrane for Advanced Tissue Engineering

Advancements in the field of tissue engineering have led to the elucidation of physical and chemical characteristics of physiological basement membranes (BM) as specialized forms of the extracellular matrix. Efforts to recapitulate the intricate structure and biological composition of the BM have encountered various advancements due to its impact on cell fate, function, and regulation. More attention has been paid to synthesizing biocompatible and biofunctional fibrillar scaffolds that closely mimic the natural BM. Specific modifications in biomimetic BM have paved the way for the development of in vitro models like alveolar-capillary barrier, airway models, skin, blood-brain barrier, kidney barrier, and metastatic models, which can be used for personalized drug screening, understanding physiological and pathological pathways, and tissue implants. In this Review, we focus on the structure, composition, and functions of in vivo BM and the ongoing efforts to mimic it synthetically. Light has been shed on the advantages and limitations of various forms of biomimetic BM scaffolds including porous polymeric membranes, hydrogels, and electrospun membranes This Review further elaborates and justifies the significance of BM mimics in tissue engineering, in particular in the development of in vitro organ model systems.

Can Heart Valve Decellularization Be Standardized? A Review of the Parameters Used for the Quality Control of Decellularization Processes

When a tissue or an organ is considered, the attention inevitably falls on the complex and delicate mechanisms regulating the correct interaction of billions of cells that populate it. However, the most critical component for the functionality of specific tissue or organ is not the cell, but the cell-secreted three-dimensional structure known as the extracellular matrix (ECM). Without the presence of an adequate ECM, there would be no optimal support and stimuli for the cellular component to replicate, communicate and interact properly, thus compromising cell dynamics and behaviour and contributing to the loss of tissue-specific cellular phenotype and functions. The limitations of the current bioprosthetic implantable medical devices have led researchers to explore tissue engineering constructs, predominantly using animal tissues as a potentially unlimited source of materials. The high homology of the protein sequences that compose the mammalian ECM, can be exploited to convert a soft animal tissue into a human autologous functional and long-lasting prosthesis ensuring the viability of the cells and maintaining the proper biomechanical function. Decellularization has been shown to be a highly promising technique to generate tissue-specific ECM-derived products for multiple applications, although it might comprise very complex processes that involve the simultaneous use of chemical, biochemical, physical and enzymatic protocols. Several different approaches have been reported in the literature for the treatment of bone, cartilage, adipose, dermal, neural and cardiovascular tissues, as well as skeletal muscle, tendons and gastrointestinal tract matrices. However, most of these reports refer to experimental data. This paper reviews the most common and latest decellularization approaches that have been adopted in cardiovascular tissue engineering. The efficacy of cells removal was specifically reviewed and discussed, together with the parameters that could be used as quality control markers for the evaluation of the effectiveness of decellularization and tissue biocompatibility. The purpose was to provide a panel of parameters that can be shared and taken into consideration by the scientific community to achieve more efficient, comparable, and reliable experimental research results and a faster technology transfer to the market.