A Comparison of 3 Bioinks for 3D Bioprinting of Articular Cartilage

Background: 3D printing has become a promising tool for cartilage engineering, combining 3D deposition of cells seeded in supporting biomaterials. Objective: Our goal was to evaluate the chondrogenic properties of three different bioinks, seeded with human bone marrow mesenchymal stem cells (bMSCs). Methods: The three different tested bioinks are seeded with 2 × 106 cells/mL bMSCs. The bioink#1 is composed of gelatin, fibrinogen, and very low viscosity alginate. The bioink#2 has the same composition, excepted for the alginate that is a low viscosity one. The bioink#3 is manufactured by CELLINK®. The cartilaginous substitutes were cultivated for 28 days in the presence of ITS vs TGF-ß1. The extracellular matrix synthesis is evaluated at D28 by histology (Hematoxylin-Eosin-Saffron & Alcian Blue) and immunostaining (type II collagen). Results: The bioink#1 better promoted type II collagen synthesis, although the three bioink were equipotent in terms of proteoglycan content. Despite its universal characteristics, the bioink#3 failed to encourage the hyaline-like matrix synthesis. Conclusion: The bioink#1 containing gelatin, fibrinogen, and very low viscosity seems to be the fittest of the three bio-inks to obtain a cartilaginous substitute presenting a remarkable matrix synthesis. This study confirms the importance of the choice of bioink for cartilage engineering.

Cell Therapy and Peripheral Artery Disease: Diabetics first!

Drawing on our clinical expertise with diabetic patients and on a retrospective study focused on patients with foot ulcers or wounds and Peripheral Artery Disease, we show a healing problem exists specifically in diabetic patients, despite arterial revascularization. To overcome this specific problem, Cell Therapy could be a way, exclusively aimed at diabetic patients. We explain the reasons why, as well as the ways and means, and more particularly the concept of tissue reversibility.

Umbilical Mesenchymal Stem Cell-Derived Extracellular Vesicle Conditioning Has an Immunosuppressive Effect on NK Cells

Background: In peripheral blood, human natural killer (NK) cells are immunological cells that nearly don’t express the ectonucleotidase CD73 on their plasma membrane. When exposed to mesenchymal stem cells (MSCs), NK cells are able to acquire CD73. MSCs are known to be CD73-positive (CD73+) and also to modulate the immune system, e.g. through adenosynergic pathway by ectonucleosidases, such as CD73. Extracellular vesicles (EVs) are involved in cell-to-cell communication. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) have emerged as paracrine mediators that are part of MSC immunomodulatory effects including immunosuppressive properties and immune privilege. Objective: The aim of our work was to study if CD73 could be acquired by NK cells through cell-to-cell communication with MSC-EVs as cell culture additives. We also hypothesised that MSC-EVs would act as tolerance inducers to attenuate NK cell cytotoxicity. Methods: Cell isolation was made from human umbilical cords for MSCs and from human peripheral blood for NK cells. MSC-EVs were isolated by ultracentrifugation and filtration, then characterized by nanoparticle tracking assay and flow cytometry (CD9, 63, 81 and 73). MSC-EV interaction with NK cells was monitored by PKH67 staining. NK cell activation was followed by measuring the expression of CD73 and NK-activating receptor natural-killer group 2, member D (NKG2D) by flow cytometry. The cytotoxicity of NK cells or EV-conditioned NK cells was evaluated after co-culture with K562 cells. Results: We showed that MSC-EVs are nanoparticles able to express CD73 and interact with NK cells. MSC-EV conditioned NK cells seem to increase CD73 and decrease NKG2D through an EV-mediated mechanism. MSC-EVs have an immunosuppressive effect on NK cells by preventing NK cell activation and NK cell cytotoxicity towards K562 cells. Conclusions: Our results demonstrate that MSC-EVs could influence NK cell behaviour and act as immunosuppressant cell-based products.

Clinical Application of Platelet-Rich Plasma Gel (PRP) in Trauma Wounds of Extremities

Research purposes: Autologous platelet-rich plasma gel (Platelet-Rich Plasma, PRP) was prepared and used for transplantation for the treatment of traumatic trauma wounds of extremities. Explore platelet-rich plasma gel (PRP) to promote the healing of exposed bone and tendon wounds. Methods: Fifteen patients with extremity bone and tendon exposed wounds were treated with autologous platelet-rich plasma gel (PRP) transplantation to observe the wound healing rate and wound healing time. Results: Among the 15 patients, 8 cases healed directly, 7 cases had active granulation growth, and second-stage skin graft wound healing; the wound healing rate was 100%, and the average wound healing time was 36 days. Conclusion: Autologous platelet-rich plasma gel (PRP) transplantation for the treatment of traumatic trauma hard wounds of the extremities, can inhibit the bacterial growth of the wounds, effectively promote the repair of soft tissue defects and accelerate the healing of bone and tendon wounds of the extremities.

Investigation of the Stem Cells Used in Modeling Human Placental Trophoblast

Human placenta is vital for fetal development, and act as an interface between the fetus and the expecting mother. Abnormal placentati on underpins various pregnancy complications such as miscarriage, pre-eclampsia and intrauterine growth restriction. Despite the important role of placenta, the molecular mechanisms governing placental formation and trophoblast cell lineage specification is poorly understand. It is mostly due to the lack of appropriate model system. The great various in placental types across mammals make it limit for the use of laboratory animals in studying human placental development. However, over the past few years, alternative methods have been employed, including human embryonic stem cells, induced pluripotent stem cells, human trophoblast stem cell, and 3-dimensional organoids. Herein, we summarize the present knowledge about human development, differentiated cell types in the trophoblast epithelium and current human placental trophoblast model systems.

Magnetic Resonance Elastography and Portal Hypertension: Influence of the Portal Venous Flow on the Liver Stiffness

The invasive measurement of the hepatic venous pressure gradient is still considered as the reference method to assess the severity of portal hypertension. Even though previous studies have shown that the liver stiffness measured by elastography could predict portal hypertension in patients with chronic liver disease, the mechanisms behind remain today poorly understood. The main reason is that the liver stiffness is not specific to portal hypertension and is also influenced by concomitant pathologies, such as cirrhosis. Portal hypertension is also source of a vascular incidence, with a substantial diversion of portal venous blood to the systemic circulation, bypassing the liver. This study focuses on this vascular effect of portal hypertension. We propose to generate and control the portal venous flow (to isolate the modifications in the portal venous flow as single effect of portal hypertension) in an anesthetized pig and then to quantify its implications on liver stiffness by an original combination of MRE and 4D-Flow Magnetic Resonance Imaging (MRI). A catheter balloon is progressively inflated in the portal vein and the peak flow, peak velocity magnitude and liver stiffness are quantified in a 1.5T MRI scanner (AREA, Siemens Healthcare, Erlangen, Germany). A strong correlation is observed between the portal peak velocity magnitude, the portal peak flow or the liver stiffness and the portal vein intraluminal obstruction. Moreover, the comparison of mechanical and flow parameters highlights a correlation with the possibility of identifying linear relationships. These results give preliminary indications about how liver stiffness can be affected by portal venous flow and, by extension, by hypertension.

In-Situ Forming Implants Loaded with Chlorhexidine and Ibuprofen for Periodontal Treatment: Proof of Concept Study In Vivo

Control of infection and inflammation is crucial for the success of periodontal treatment. In this study, in-situ forming implants (ISFI) loaded with chlorhexidine dihydrochloride (CHX) and ibuprofen (IBU) were developed and tested to optimize periodontal treatment outcomes. Release profiles were promising. Exposure to 1.5% and 5.3% CHX-IBU loaded ISFI’s release media decreased significantly the P. gingivalis growth up to 20-fold and 35-fold, respectively, after 48 h (p<0.05). The metabolic activity assay of gingival epithelial cells (EC) demonstrated 1.5% CHX-IBU-loaded ISFI to be non-toxic, therefore, it was selected for further experimentation. Furthermore, significant down-regulation of TNF-α release (34% at 6 h and 43% at 24 h, p<0.05) in P.gingivalis lipopolysaccharide (Pg-LPS) stimulated EC exposed to 1.5% CHX-IBU ISFI release medium was demonstrated by ELISA. In vivo, 1.5% CHX-IBU ISFI was injected into the periodontal pocket in an experimental periodontitis mouse model and the reduction in inflammation and improvement in periodontal wound healing was evaluated through inflammatory cell scoring and histomorphometry at 7- and 15-days post-treatment. The results indicate that CHX-IBU loaded ISFI could be efficient as adjuvant to periodontal therapy for the control of infection and inflammation. Moreover, other (e.g., pro-regenerative) drugs could be incorporated into ISFI to further improve periodontal treatment outcomes.