Generation of bioartificial hearts using decellularized scaffolds and mixed cells.

BACKGROUND: Patients with end-stage heart failure must receive treatment to recover cardiac function, and the current primary therapy, heart transplantation, is plagued by the limited supply of donor hearts. Bioengineered artificial hearts generated by seeding of cells on decellularized scaffolds have been suggested as an alternative source for transplantation. This study aimed to develop a tissue-engineered heart with lower immunogenicity and functional similarity to a physiological heart that can be used for heart transplantation. MATERIALS AND METHODS: We used sodium dodecyl sulfate (SDS) to decellularize cardiac tissue to obtain a decellularized scaffold. Mesenchymal stem cells (MSCs) were isolated from rat bone marrow and identified by flow cytometric labeling of their surface markers. At the same time, the multi-directional differentiation of MSCs was analyzed. The MSCs, endothelial cells, and cardiomyocytes were allowed to adhere to the decellularized scaffold during perfusion, and the function of tissue-engineered heart was analyzed by immunohistochemistry and electrocardiogram. RESULTS: MSCs, isolated from rats differentiated into cardiomyocytes, were seeded along with primary rat cardiomyocytes and endothelial cells onto decellularized rat heart scaffolds. We first confirmed the pluripotency of the MSCs, performed immunostaining against cardiac markers expressed by MSC-derived cardiomyocytes, and completed surface antigen profiling of MSC-derived endothelial cells. After cell seeding and culture, we analyzed the performance of the bioartificial heart by electrocardiography but found that the bioartificial heart exhibited abnormal electrical activity. The results indicated that the tissue-engineered heart lacked some cells necessary for the conduction of electrical current, causing deficient conduction function compared to the normal heart. CONCLUSION: Our study suggests that MSCs derived from rats may be useful in the generation of a bioartificial heart, although technical challenges remain with regard to generating a fully functional bioartificial heart.

Selective Binding to mRNA Duplex Regions by Chemically Modified Peptide Nucleic Acids Stimulates Ribosomal Frameshifting.

Minus-one programmed ribosomal frameshifting (-1 PRF) allows the precise maintenance of the ratio between viral proteins and is involved in the regulation of the half-lives of cellular mRNAs. Minus-one ribosomal frameshifting is activated by several stimulatory elements such as a heptameric slippery sequence (X XXY YYZ) and an mRNA secondary structure (hairpin or pseudoknot) that is positioned 2-8 nucleotides downstream from the slippery site. Upon -1 RF, the ribosomal reading frame is shifted from the normal zero frame to the -1 frame with the heptameric slippery sequence decoded as XXX YYY Z instead of X XXY YYZ. Our research group has developed chemically modified peptide nucleic acid (PNA) L and Q monomers to recognize G-C and C-G Watson-Crick base pairs, respectively, through major-groove parallel PNA·RNA-RNA triplex formation. L- and Q-incorporated PNAs show selective binding to double-stranded RNAs (dsRNAs) over single-stranded RNAs (ssRNAs). The sequence specificity and structural selectivity of L- and Q-modified PNAs may allow the precise targeting of desired viral and cellular RNA structures, and thus may serve as valuable biological tools for mechanistic studies and potential therapeutics for fighting diseases. Here, for the first time, we demonstrate by cell-free in vitro translation assays using rabbit reticulocyte lysate that the dsRNA-specific chemically modified PNAs targeting model mRNA hairpins stimulate -1 RF (from 2% to 32%). An unmodified control PNA, however, shows nonspecific inhibition of translation. Our results suggest that the modified dsRNA-binding PNAs may be advantageous for targeting structured RNAs.

Single-Molecule Mechanical Folding and Unfolding of RNA Hairpins: Effects of Single A-U to A·C Pair Substitutions and Single Proton Binding and Implications for mRNA Structure-Induced -1 Ribosomal Frameshifting.

A wobble A·C pair can be protonated at near physiological pH to form a more stable wobble A+·C pair. Here, we constructed an RNA hairpin (rHP) and three mutants with one A-U base pair substituted with an A·C mismatch on the top (near the loop, U22C), middle (U25C), and bottom (U29C) positions of the stem, respectively. Our results on single-molecule mechanical (un)folding using optical tweezers reveal the destabilization effect of A-U to A·C pair substitution and protonation-dependent enhancement of mechanical stability facilitated through an increased folding rate, or decreased unfolding rate, or both. Our data show that protonation may occur rapidly upon the formation of an apparent mechanical folding transition state. Furthermore, we measured the bulk -1 ribosomal frameshifting efficiencies of the hairpins by a cell-free translation assay. For the mRNA hairpins studied, -1 frameshifting efficiency correlates with mechanical unfolding force at equilibrium and folding rate at around 15 pN. U29C has a frameshifting efficiency similar to that of rHP (∼2%). Accordingly, the bottom 2-4 base pairs of U29C may not form under a stretching force at pH 7.3, which is consistent with the fact that the bottom base pairs of the hairpins may be disrupted by ribosome at the slippery site. U22C and U25C have a similar frameshifting efficiency (∼1%), indicating that both unfolding and folding rates of an mRNA hairpin in a crowded environment may affect frameshifting. Our data indicate that mechanical (un)folding of RNA hairpins may mimic how mRNAs unfold and fold in the presence of translating ribosomes.

A case report of chyle leakage after axillary node clearance in a patient with breast cancer.

Key Clinical Message: Chyle leakage is a rare postoperative complication of breast cancer, and conservative treatments should be prioritized, with careful monitoring of drainage volume and timely surgical intervention when conservative treatments are ineffective. Abstract: Chyle leaks following surgery for breast cancer are seldom encountered. Management varies with no consensus in the literature. This paper reports a case of a chylous leak after axillary dissection in a patient with breast cancer eventually cured with conservative treatment and discusses management options varied with both conservative and surgical options available to clinicians.

Advances in the construction and application of konjac glucomannan-based delivery systems.

Konjac glucomannan (KGM) has been widely used to deliver bioactive components due to its naturalness, non-toxicity, excellent biodegradability, biocompatibility, and other characteristics. This review presents an overview of konjac glucomannan as a matrix, and the types of konjac glucomannan-based delivery systems (such as hydrogels, food packaging films, microencapsulation, emulsions, nanomicelles) and their construction methods are introduced in detail. Furthermore, taking polyphenol compounds, probiotics, flavor substances, fatty acids, and other components as representatives, the applied research progress of konjac glucomannan-based delivery systems in food are summarized. Finally, the prospects for research directions in konjac glucomannan-based delivery systems are examined, thereby providing a theoretical basis for expanding the application of konjac glucomannan in other industries, such as food and medicine.

Enhanced stabilization of multifunctional phenolic acids-grafted chitin nanofibers for Pickering emulsions.

The objective of this study was to develop novel functional stabilizers for Pickering emulsions using phenolic acids-grafted chitin nanofibers (phenolic acids-g-ChNF), which were fabricated by grafting ferulic acid (FA), sinapic acid (SA) and caffeic acid (CA) onto ChNF via free radical-mediated method. The Fourier transform infrared spectrum and Proton nuclear magnetic resonance showed that graft copolymerization occurred between the amino groups of ChNF and the carbonyl of the phenolic acids. Further, it was revealed that CA-g-ChNF and SA-g-ChNF possessed stronger antioxidant and antibacterial properties than the original ChNF and FA-g-ChNF. Additionally, we applied phenolic acids-g-ChNF to develop Pickering emulsions and found that SA-g-ChNF- and CA-g-ChNF-stabilized emulsions displayed reduced droplet sizes compared to FA, the main reason for which was that SA and CA had a rather close bonding relationship with ChNF. Taken together, SA-g-ChNF and CA-g-ChNF as novel multi-functional particles can be employed for facilitating the stability of Pickering emulsions.

General requirements for the production of extracellular vesicles derived from human stem cells.

'General requirements for the production of extracellular vesicles derived from human stem cells' is the first guideline for stem cells derived extracellular vesicles in China, jointly drafted and agreed upon by experts from the Chinese Society for Stem Cell Research. This standard specifies the general requirements, process requirements, packaging and labelling requirements and storage requirements for preparing extracellular vesicles derived from human stem cells, which is applicable to the research and production of extracellular vesicles derived from stem cells. It was originally released by the China Society for Cell Biology on 30 August 2022. We hope that the publication of this guideline will promote institutional establishment, acceptance and execution of proper protocols, and accelerate the international standardisation of extracellular vesicles derived from human stem cells.

Immobilization of phlorotannins on nanochitin: A novel biopreservative for refrigerated sea bass (Lateolabrax japonicus) fillets.

A novel biopreservative was developed by immobilizing phlorotannins into nanochitin (NCh). NCh were selected as a host complex to immobilized phlorotannins and the structural properties and antioxidant activity of the NCh-phlorotannins nanocomplex was investigated. The NCh-phlorotannins showed high antioxidant activity, as evidenced by free radical scavenging activity test. Moreover, the effects of NCh-phlorotannins on physical [color, water holding capacity (WHC), and texture], chemical [thiobarbituric acid (TBA) values, total volatile base nitrogen (TVB-N), and pH], microbiological [total viable count], changes of refrigerated sea bass (Lateolabrax japonicus) fillets were also evaluated. Sea bass fillets add with 1.5 g/kg NCh-phlorotannins had lower bacterial growth, pH, TVB-N and TBA as well as better characteristics of texture, color, and WHC than those of the control group during refrigerated storage. The efficiency of NCh-phlorotannins treatment was also better than that of phlorotannins or NCh treatment alone. Therefore, NCh-phlorotannins may be a potential biopreservative to extend the shelf-life of sea bass fillets quality during refrigerated storage.

Oxidized Chitin Nanocrystals Greatly Strengthen the Stability of Resveratrol-Loaded Gliadin Nanoparticles.

Resveratrol (RES) is a natural polyphenol with a variety of health beneficial properties, but its application is greatly limited due to low aqueous solubility and poor bioavailability. This study aims to address these issues via gliadin nanoparticles stabilized with oxidized chitin nanocrystals (O-ChNCs) as a delivery system for RES. RES-loaded gliadin nanoparticles (GRNPs) were fabricated by an antisolvent method, and their formation mechanism was elucidated using zeta-potential, FTIR, XRD, and TEM. Furthermore, the effect of O-ChNCs on the colloidal stability and bioactiveness of GRNPs was discussed. The results demonstrate that O-ChNCs are adsorbed onto the surface of GRNPs through hydrogen bonding and electrostatic interactions, leading to the enhanced absolute potential and the improved hydrophobicity of the particles, which in turn facilitates the stability of the GRNPs. Furthermore, the changes in the release profile and antioxidant activity of RES in the simulated gastric and intestinal tracts indicate that the adsorption of O-ChNCs not only delays the release of RES but also has a protective effect on the antioxidant capacity of RES. This study provides significant implications for developing stable gliadin nanoparticles as delivery vehicles for bioactive substances.

Cytoplasm or Supernatant: Where Is the Treasury of the Bioactive Antiaging Factor from Mesenchymal Stem Cells?

Cell-free compounds of mesenchymal stem cells (MSCs) could be a safer and cheaper substitution for MSC transplantation and have gained substantial research interest for antiaging skin treatments. However, whether those bioactive components should be obtained from the cytoplasm or supernatant is yet to be determined. In this study, we examined the ingredients of the MSC cytoplasm extract (MSC-ex) and MSC supernatant (MSC-s) and evaluated their effect in a photoaging model. Although MSC-ex has a richer protein composition than MSC-s, the latter has a proteome associated with wound healing and blood vessel development. Over 85% of the proteins in MSC-s were also found in MSC-ex, including extracellular matrix protein and various growth factors. The results of real-time PCR and western blot also demonstrate that both MSC-s and MSC-ex can upregulate collagen, transforming growth factor ß (TGF-ß), and vascular endothelial growth factor (VEGF) and downregulate IL-1ß and matrix metalloproteinase-1 (MMP-1), which were considered critical for antiphotoaging. This supports our observations in the Hematoxylin and Eosin (HE) and Masson staining assay that they have a comparable effect as MSCs in terms of enhancing dermal thickness, and stimulating collagen regeneration. Although MSC-s and MSC-ex showed a weaker immunosuppression effect than MSCs, moisture measurement showed that they repair damage more rapidly than MSCs. Furthermore, the histological results showed that MSC-s maintains a super effect on immunosuppression, epidermal repair, and angiogenesis. That may be associated with the higher content of laminin, TGF-ß, and VEGF in MSC-s, as well as its super cytokine transcriptional regulation ability. Thus, both MSC-s and MSC-ex can safely and effectively promote the repair of skin light injury, similar to MSCs. Our findings can broaden the range of active factors available in cell-free treatment, determine the difference between MSC-s and MSC-ex, and provide a reference for the development of similar products in regenerative medicine.

Safety and biodistribution of exosomes derived from human induced pluripotent stem cells.

As a new cell-free therapy, exosomes have provided new ideas for the treatment of various diseases. Human induced pluripotent stem cells (hiPSCs) cannot be used in clinical trials because of tumorigenicity, but the exosomes derived from hiPSCs may combine the advantages of iPSC pluripotency and the nanoscale size of exosomes while avoiding tumorigenicity. Currently, the safety and biodistribution of hiPSC-exosomes in vivo are unclear. Here, we investigated the effects of hiPSC-exosomes on hemolysis, DNA damage, and cytotoxicity through cell experiments. We also explored the safety of vein injection of hiPSC-exosomes in rabbits and rats. Differences in organ distribution after nasal administration were compared in normal and Parkinson's disease model mice. This study may provide support for clinical therapy and research of intravenous and nasal administration of hiPSC-exosomes.

Development and characterization of electrospun nanofibers based on pullulan/chitin nanofibers containing curcumin and anthocyanins for active-intelligent food packaging.

An electrospun nanofiber based on pullulan/chitin nanofibers (PCN) containing curcumin (CR) and anthocyanins (ATH) was developed using an electrospinning technique for active-intelligent food packaging. The results of scanning electron microscopy and attenuated total reflection Fourier transform infrared spectroscopy indicated that CR and ATH were successfully immobilized on the film-forming substrate based on PCN. The physical and chemical properties of nanofibers with no colorant, a single colorant, and double colorants were compared. The nanofiber containing ATH and CR (PCN/CR/ATH) had stronger antioxidant and antimicrobial activities than those of nanofibers containing CR (PCN/CR) or ATH (PCN/ATH). With respect to pH sensitivity, the color of the PCN/CR nanofibers did not change obviously, but the color of the PCN/ATH and PCN/CR/ATH nanofibers changed significantly with the change in pH. Furthermore, the PCN/CR/ATH nanofibers clearly changed color with the progressive spoilage of Plectorhynchus cinctus at room temperature. Therefore, the electrospun PCN/CR/ATH nanofiber have great application potential in active-intelligent food packaging.

Investigation of the structural and physical properties, antioxidant and antimicrobial activity of konjac glucomannan/cellulose nanocrystal bionanocomposite films incorporated with phlorotannin from Sargassum.

In this study, environmentally friendly bionanocomposite films were prepared by incorporating phlorotannins from Sargassum (PS) into konjac glucomannan (KGM)/cotton cellulose nanocrystals (CNC) composites. The effects of different concentrations of PS (5%, 9%, 13%, and 17%, w/w) on the microstructure, physical properties, antioxidant and antibacterial activities of the resultant bionanocomposite films were evaluated. The results of scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectra showed that PS was well compatible with the KGM/CNC composites matrix, which led to form a compact and uniform structure of the films. Thermogravimetric analysis and differential scanning calorimetry demonstrated that incorporating PS improved the heat stability of KGM/CNC bionanocomposite films. And addition of the appropriate amount of PS improved the mechanical and water-vapor barrier-related properties of the bionanocomposite film. For instance, with 9% PS, the tensile strength of the KGM/CNC/PS bionanocomposite film increased by 33.9%, and the water-vapor transmittance decreased by 41.67% compared to that of the KGM/CNC films. Moreover, the addition of PS endowed the KGM/CNC film with excellent antioxidant and antibacterial properties. Therefore, KGM/CNC/PS bionanocomposite films have great potential to be applicated as active packaging in the food packaging industry.

Mechanical emulsification of lipoaspirate by different Luer-Lok connector changes the viability of adipose derived stem cells in Nanofat.

Nanofat grafting is a fat transfer procedure that uses a thin needle to smooth out wrinkles, thereby achieving the goal of skin rejuvenation. The Luer-Lok connector is one of the most common methods for obtaining Nanofat. In the present study, we compared three different Luer-Lok connectors (2.0 mm, 1.5 mm and 1.1 mm in diameter) in terms of their impact on the viability of adipose-derived stem cells (ADSCs) to determine the optimal size of the connector for efficient Nanofat grafting. We observed that a smaller diameter of the Luer-Lok connector created a higher mechanical shear force, which broke more fat cells during the emulsifying procedure, thereby reducing the viability of ADSCs from the stromal vascular fraction (SVF). Nanofat obtained from the 2-mm Luer-Lok connector had a better effect on skin rejuvenation than the 1.5-mm and 1.1-mm connectors. Therefore, this study presents an advance in the simple procedure of preparing Nanofat based on a previous technique and provides evidence that a procedure associated with less trauma may be a better choice.

Effect of carboxylation cellulose nanocrystal and grape peel extracts on the physical, mechanical and antioxidant properties of konjac glucomannan films.

Active bionanocomposite films were prepared by incorporating konjac glucomannan (KGM) as a matrix, with carboxylation cellulose nanocrystal (C-CNC) as a reinforcement agent and grape peel extracts (GPE) as a natural antioxidation agent. The effects of C-CNC and/or GPE addition on the structural, morphological, barrier, thermal, mechanical and antioxidant properties of the bionanocomposite films were investigated. The rheological results of film forming solutions revealed that C-CNC and GPE were well dispersed in the KGM matrix. Scanning electron micrographs observed the addition of C-CNC had little effect on the microstructure, while more roughness and unevenness were observed on the film surface and cross-section with the C-CNC and GPE. Furthermore, the water vapor barrier property and transparency of the films improved by the addition of the C-CNC and GPE. Notably, the incorporating of C-CNC or GPE significantly alter the mechanical of the KGM/C-CNC/GPE bionanocomposite films. The highest tensile strength was achieved for the KGM/GPE bionanocomposite film with 10 wt% C-CNC, indicating C-CNC and GPE had synergistic effect on enhancing the TS of KGM film. Moreover, the KGM/C-CNC/GPE films exhibited strong antioxidant activity. These results suggested that KGM/C-CNC/GPE bionanocomposite films can be used as an active food packaging for increasing shelf life of packaged foods.

Immunogenicity analysis of decellularized cardiac scaffolds after transplantation into rats.

Aim: Cardiac extracellular matrix (cECM) scaffolds are promising biomaterials for clinical applications. Our aim is to determine the immunogenicity of decellularized scaffolds from different sources for use as artificial organs during organ transplantation. Materials & methods: We transplanted Lewis rats with syngeneic (Lewis rat cECM), allogeneic (BN rat cECM) or xenogeneic (hamster cECM) decellularized cardiac scaffolds. Acute vascular and cellular rejection was quantified by immunohistochemistry and immune cell infiltration. Results: BN rat and hamster hearts were rejected following transplantation. BN and hamster cECMs had similarly low immunogenicity compared with Lewis rat cECMs and did not lead to increased rejection. Conclusion: We found that scaffolds from all sources did not induce vascular or cellular rejection and exhibited low immunogenicity.