An evaluation of a polyethersulfone hollow fiber plasma separator by animal experiment

Biocompatibility evaluation of polyethersulfone-pyrolytic carbon composite membrane in artificial pancreas

Polyethersulfone (PES) membranes are widely used in medical devices, especially intravascular devices such as intravascular bioartificial pancreases. In the current work, the pure PES and PES-pyrolytic carbon (PyC) composite membranes were synthesized and permeability studies were conducted. In addition, the cytocompatibility and hemocompatibility of the pure PES and PES-PyC membranes were investigated. These materials were characterized using peripheral blood mononuclear cell (PBMC) activation, platelet activation, platelet adhesion, ß-cell viability and proliferation, and ß-cell response to hyperglycemia. The results showed that platelet activation decreased from 87.3% to 27.8%. Any alteration in the morphology of sticking platelets was prevented, and the number of attached platelets decreased by modification with PyC. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay corroborated that PBMC activation was encouraged by the PyC-modified PES membrane surface. It can be concluded that PES-modified membranes show higher hemocompatibility than pure PES membranes. ß-cells cultured on all the three membranes displayed a lower rate of proliferation although the cells on the PES-PyC (0.1 wt. %) membrane indicated a slightly higher viability and proliferation than those on the pure PES and PES-PyC (0.05 wt. %) membranes. It shows that the PES-PyC (0.1 wt. %) membrane possesses superior cytocompatibility over the other membranes.

Current approaches for the regeneration and reconstruction of ocular surface in dry eye

Significant research revealed the preocular tear film composition and regulations that remain vital for maintaining Ocular surface functional integrity. Inflammation triggered by many factors is the hallmark of Ocular surface disorders or dry eyes syndrome (DES). The tear deficiencies may lead to ocular surface desiccation, corneal ulceration and/or perforation, higher rates of infectious disease, and the risk of severe visual impairment and blindness. Clinical management remains largely supportive, palliative, and frequent, lifelong use of different lubricating agents. However, few advancements such as punctal plugs, non-steroidal anti-inflammatory drugs, and salivary gland autografts are of limited use. Cell-based therapies, tissue engineering, and regenerative medicine, have recently evolved as long-term cures for many diseases, including ophthalmic diseases. The present article focuses on the different regenerative medicine and reconstruction/bioengineered lacrimal gland formation strategies reported so far, along with their limiting factors and feasibility as an effective cure in future.

In vivo transcriptomic profiling using cell encapsulation identifies effector pathways of systemic aging

Sustained exposure to a young systemic environment rejuvenates aged organisms and promotes cellular function. However, due to the intrinsic complexity of tissues it remains challenging to pinpoint niche-independent effects of circulating factors on specific cell populations. Here, we describe a method for the encapsulation of human and mouse skeletal muscle progenitors in diffusible polyethersulfone hollow fiber capsules that can be used to profile systemic aging in vivo independent of heterogeneous short-range tissue interactions. We observed that circulating long-range signaling factors in the old systemic environment lead to an activation of Myc and E2F transcription factors, induce senescence, and suppress myogenic differentiation. Importantly, in vitro profiling using young and old serum in 2D culture does not capture all pathways deregulated in encapsulated cells in aged mice. Thus, in vivo transcriptomic profiling using cell encapsulation allows for the characterization of effector pathways of systemic aging with unparalleled accuracy.

Flux and Passage Enhancement in Hemodialysis by Incorporating Compound Additive into PVDF Polymer Matrix

In this study, Polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were prepared by non-solvent induced phase separation (NIPS) with compound addtive. The compound additive was made with polyvinyl pyrrolidone (PVP) and Poly ethylene glycol (PEG). The results showed that the modified PVDF membrane had better separation performance than virgin PVDF membrane. The UF flux of modified PVDF membrane can reach 684 L·h⁻¹·m⁻² and lysozyme (LZM) passage is 72.6% while virgin PVDF membrane is 313 L·h⁻¹·m⁻² and 53.2%. At the same time, the biocompatibility of PVDF membranes was also improved. Compared with commercial polysulfone hemodialysis membrane (Fresenius F60S membrane), the modified PVDF membrane had better mechanical and separation performance. The stress and tensile elongation of modified PVDF membrane was 0.94 MPa and 352% while Fresenius F60S membrane was 0.79 MPa and 59%. The LZM passage reached 72.6% while Fresenius F60S membrane was 54.4%. It was proven that the modified PVDF membrane showed better hydrophilicity, antithrombogenicity, less BSA adsorption, and lower hemolytic ratio and adhesion of platelets. Water contact angle and BSA adsorption of the modified PVDF membrane are 38° and 45 mg/m² while Fresenius F60S membrane are 64° and 235 mg/m². Prothrombin time (PT) and activated partial thromboplastin time (APTT) of the modified PVDF membrane are 56.5 s and 25.8 s while Fresenius F60S membrane is 35.7 s and 16.6 s. However, further biocompatibility evaluation is needed to obtain a more comprehensive conclusion.

Preparation and preliminary dialysis performance research of polyvinylidene fluoride hollow fiber membranes

In this study, the separation properties of Polyvinylidene fluoride (PVDF) hollow fiber hemodialysis membranes were improved by optimizing membrane morphology and structure. The results showed that the PVDF membrane had better mechanical and separation properties than Fresenius Polysulfone High-Flux (F60S) membrane. The PVDF membrane tensile stress at break, tensile elongation and bursting pressure were 11.3 MPa, 395% and 0.625 MPa, respectively. Ultrafiltration (UF) flux of pure water reached 108.2 L∙h⁻¹∙m⁻² and rejection of Albumin from bovine serum was 82.3%. The PVDF dialyzers were prepared by centrifugal casting. The influences of membrane area and simulate fluid flow rate on dialysis performance were investigated. The results showed that the clearance rate of urea and Lysozyme (LZM) were improved with increasing membrane area and fluid flow rate while the rejection of albumin from bovine serum (BSA) had little influence. The high-flux PVDF dialyzer UF coefficient reached 62.6 mL/h/mmHg. The PVDF dialyzer with membrane area 0.69 m² has the highest clearance rate to LZM and urea. The clearance rate of LZM was 66.8% and urea was 87.7%.

Antithrombogenicity of Fluorinated Diamond-Like Carbon Films Coated Nano Porous Polyethersulfone (PES) Membrane

A nano porous polyethersulfone (PES) membrane is widely used for aspects of nanofiltration, such as purification, fractionation and dialysis. However, the low-blood-compatibility characteristic of PES membrane causes platelets and blood cells to stick to the surface of the membrane and degrades ions diffusion through membrane, which further limits its application for dialysis systems. In this study, we deposited the fluorinated-diamond-like-carbon (F-DLC) onto the finger like structure layer of the PES membrane. By doing this, we have the F-DLC films coating the membrane surface without sacrificing the membrane permeability. In addition, we examined antithrombogenicity of the F-DLC/PES membranes using a microfluidic device, and experimentally found that F-DLC drastically reduced the amount of blood cells attached to the surface. We have also conducted long-term experiments for 24 days and the diffusion characteristics were found to be deteriorated due to fouling without any surface modification. On the other hand, the membranes coated by F-DLC film gave a consistent diffusion coefficient of ions transfer through a membrane porous. Therefore, F-DLC films can be a great candidate to improve the antithrombogenic characteristics of the membrane surfaces in hemodialysis systems.