Effect of amino acids near the RGD sequence on binding activities between αIIbβ3 integrin and fibrinogen in the presence of RGD-containing synthetic peptides from elegantin and angustatin

SKOV-3 Cell Aggregates on a Microfluidic Chip with a Thermoresponsive Hydrogel as a Culture Scaffold for DOX Assessment

Microfluidic chip technology is very popular in life sciences. Here, ovarian cancer SKOV-3 cell aggregates were formed using thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid) (PNA) hydrogel as a culture scaffold on a microfluidic chip serving as an operating platform. A simple microfluidic chip was designed and fabricated as the three-dimensional (3D) cell culture microplatform. Different concentrations of doxorubicin (DOX) were fed to the obtained SKOV-3 cell aggregates on the chip via a pump. All characterization results indicated that this system could effectively perform 3D cell culture and drug evaluation to a certain extent. In addition, by grafting the RGD sequence, the biocompatibility of the PNA hydrogel was improved. On the one hand, the grafting of the RGD sequence into the hydrogel could significantly improve cell proliferation in this system; on the other hand, it led to an earlier appearance of DOX drug resistance. This versatile model in this study has the potential for further use in in vitro human ovarian cancer physiological models, drug discovery, and toxicology research.

Generation of induced pluripotent stem cell-derived anterior foregut endoderms on integrin-binding short peptide-based synthetic substrates

Anterior foregut endoderms (AFEs) derived from induced pluripotent stem cells (iPSCs) are an important cell source in stem cell technology as they give rise to some important lineages like lung progenitors and thyroid cells. Coating substrates plays a critical role in AFE generation. Currently, conventional large molecule proteins like Matrigel are used in most differentiation protocols. However, the complex components and mechanisms of these coatings have limited both the exploration of cell-extracellular matrix (ECM) interaction and potential clinical applications. In this study, we identified eight pure synthetic integrin-binding short peptides as effective coatings for iPSC growth and AFE generation with an integrin-binding peptide array. Our results showed that integrinα5β1-,αVβ8-, andαIIbβ3-binding peptides supported the adhesion and expansion of iPSCs and AFE generation by guided differentiation via a definitive endoderm (DE) in a full-anchorage-dependent manner. AFE generation was also found on coatings based on integrinα3β1-,α6β1-,αVβ1-,αVβ6-, andαMβ2-binding peptides following a process with temporal suspension growth in the DE-inducing stage, with lower AFE generation efficiency compared to the full-anchorage-dependent peptide groups and Matrigel. According to the results, the integrinα5β1-binding peptide is the most promising defined substrate for inducing AFEs because of its equivalent efficiency with traditional Matrigel coating in supporting iPSC expansion and differentiation toward AFEs. Additionally, the other seven peptide-based coatings also exhibit potential and could be further investigated for developing synthetic-coating strategies in future studies involving AFEs. Our findings provide valuable insights into the role of integrin and ECM function and hold great potential for disease modeling as well as therapeutic exploration of AFE origin organs.

Bruch's-Mimetic Nanofibrous Membranes Functionalized with the Integrin-Binding Peptides as a Promising Approach for Human Retinal Pigment Epithelium Cell Transplantation

BACKGROUND

This study aimed to develop an ultrathin nanofibrous membrane able to, firstly, mimic the natural fibrous architecture of human Bruch's membrane (BM) and, secondly, promote survival of retinal pigment epithelial (RPE) cells after surface functionalization of fibrous membranes.

METHODS

Integrin-binding peptides (IBPs) that specifically interact with appropriate adhesion receptors on RPEs were immobilized on Bruch's-mimetic membranes to promote coverage of RPEs. Surface morphologies, Fourier-transform infrared spectroscopy spectra, contact angle analysis, Alamar Blue assay, live/dead assay, immunofluorescence staining, and scanning electron microscopy were used to evaluate the outcome.

RESULTS

Results showed that coated membranes maintained the original morphology of nanofibers. After coating with IBPs, the water contact angle of the membrane surfaces varied from 92.38 ± 0.67 degrees to 20.16 ± 0.81 degrees. RPE cells seeded on IBP-coated membranes showed the highest viability at all time points (Day 1, p < 0.05; Day 3, p < 0.01; Days 7 and 14, p < 0.001). The proliferation rate of RPE cells on uncoated poly(ε-caprolactone) (PCL) membranes was significantly lower than that of IBP-coated membranes (p < 0.001). SEM images showed a well-organized hexa/polygonal monolayer of RPE cells on IBP-coated membranes. RPE cells proliferated rapidly, contacted, and became confluent. RPE cells formed a tight adhesion with nanofibers under high-magnification SEM. Our findings confirmed that the IBP-coated PCL membrane improved the attachment, proliferation, and viability of RPE cells. In addition, in this study, we used serum-free culture for RPE cells and short IBPs without immunogenicity to prevent graft rejection and immunogenicity during transplantation.

CONCLUSIONS

These results indicated that the biomimic BM-IBP-RPE nanofibrous graft might be a new, practicable approach to increase the success rate of RPE cell transplantation.

Bioactive Molecules Derived from Snake Venoms with Therapeutic Potential for the Treatment of Thrombo-Cardiovascular Disorders Associated with COVID-19

As expected, several new variants of Severe Acute Respiratory Syndrome-CoronaVirus-2 (SARS-CoV-2) emerged and have been detected around the world throughout this Coronavirus Disease of 2019 (COVID-19) pandemic. Currently, there is no specific developed drug against COVID-19 and the challenge of developing effective antiviral strategies based on natural agents with different mechanisms of action becomes an urgent need and requires identification of genetic differences among variants. Such data is used to improve therapeutics to combat SARS-CoV-2 variants. Nature is known to offer many biotherapeutics from animal venoms, algae and plant that have been historically used in traditional medicine. Among these bioresources, snake venom displays many bioactivities of interest such as antiviral, antiplatelet, antithrombotic, anti-inflammatory, antimicrobial and antitumoral. COVID-19 is a viral respiratory sickness due to SARS-CoV-2 which induces thrombotic disorders due to cytokine storm, platelet hyperactivation and endothelial dysfunction. This review aims to: (1) present an overview on the infection, the developed thrombo-inflammatory responses and mechanisms of induced thrombosis of COVID-19 compared to other similar pathogenesis; (2) underline the role of natural compounds such as anticoagulant, antiplatelet and thrombolytic agents; (3) investigate the management of coagulopathy related to COVID-19 and provide insight on therapeutic such as venom compounds. We also summarize the updated advances on antiviral proteins and peptides derived from snake venoms that could weaken coagulopathy characterizing COVID-19.

Isolation and Functional Identification of an Antiplatelet RGD-Containing Disintegrin from Cerastes cerastes Venom

The current report focuses on purification, structural and functional characterization of Cerastategrin from Cerastes cerastes venom, a novel basic disintegrin (pI 8.36) with 128 amino acid residues and a molecular weight of 13 835.25 Da measured by MALDI-MSMS. The 3D structure of Cerastategrin is organized as α-helix (13%), β-strand (15%) and disordered structure (30%) and presents homologies with several snake venom disintegrins. Structural modeling shows that Cerastategrin presents an RGD motif that connects specifically to integrin receptors. Cerastategrin exhibits the inhibition of ADP induced platelets with an IC₅₀ of 0.88 µg/mL and shows in vivo long stable anticoagulation effect 24 h post-injection of increasing doses ranging from 0.2 to 1 mg/kg, therefore, Cerastategrin maintained irreversibly the blood incoagulable. Moreover, Cerastategrin decreases the amount of bounded αIIbβ3 and reduced significantly the quantity of externalized P-Selectin. Cerastategrin acts as a molecule targeting specifically the receptor α_IIbβ₃; therefore, it behaves as a potent platelet activation inhibitor. As a new peptide with promising pharmacological properties, Cerastategrin could have a potential therapeutical effect in the vascular pathologies and may be a new effective treatment approach.

Screening of pure synthetic coating substrates for induced pluripotent stem cells and iPSC-derived neuroepithelial progenitors with short peptide based integrin array

Simple and pure synthetic coating substrates are needed to overcome the disadvantages of traditional coating products like animal derived Matrigel in stem cell research. Since integrins are of great importance in cell adhesion and cell-ECM communication, in this study, a commercially available integrin array established by synthetic integrin binding peptides is used to screen coating substrates for iPSCs and NEPs. The results showed that binding peptides of integrin α₅β₁, α_Vβ₁, α_Mβ₂ and α_IIbβ₃ supported cell adhesion of iPSCs, while α₅β₁, α_Vβ₁ and α_IIbβ₃ binding peptides supported NEPs adhesion. Additionally, integrin α5β1 binding peptide was revealed to support rapid expansion of iPSCs and iPSC-derived NEPs, as well as the process of NEPs generation, with equal efficiency as Matrigel. In this work, we demonstrated that by supporting stem cell growth in an integrin dependent manner, the integrin array and coating system has the potential to develop more precise and efficient systems in neurological disease modeling.