August 2017 - electrospun chitosan nanofibers

In August, 320 articles about chitosan and chitosan derivatives were published in various scientific journals (PubMed). Seven of these articles are dedicated to the exciting topic of electrospun chitosan nanofibers. For generation of nanofibrous structures in tissue engineering, electrospinning is a simple and inexpensive technology. Electrospun nanofiber non-woven mats are highly porous and offer a large surface area. The biocompatible, biodegradable and bacteriostatic chitosan is perfectly suitable for creation of nanofibers and application as scaffold material.

Long-term liver-specific functions of hepatocytes in electrospun chitosan nanofiber scaffolds coated with fibronectin

Rajendran D., Hussain A., Yip D., Parekh D., Shrirao A., Cho C.H. Journal of biomedical materials research, August 2017, 105(8):2119-2128. doi: 10.1002/jbm.a.36072.

US researchers developed a 3D liver model using nanofiber scaffolds and co-culturing of hepatocytes and fibroblasts. Chitosan nanofiber scaffolds were created by eletrospinning technique and coated with fibronectin. Different cell types (primary hepatocytes from rat, 3T3-J2 fibroblasts, human hepatocellular liver carcinoma cell line (HepG2) and liver sinusoidal endothelial cells (LSEC)) were tested with 2D chitosan films with or without fibronectin. For investigation of cell attachment and spreading immunofluorescence staining and image analysis were performed. Additionally mono-cultures of hepatocytes or co-cultures with fibroblasts were seeded on circular 3D fibronectin-coated scaffolds. Characterization of cellular phenotypes, cellular adhesion and liver-specific functions of the 3D hepatic mono- and co-cultures was conducted.

RESULTS

• Electrospun chitosan scaffolds were highly porous with an average pore size of 2.2±0.4 µm and a mat thickness of around 150 µm
• Seeded cells migrated into the scaffold
• Fibronectin coating improved cellular adhesion and spreading (e.g. by polarized distribution of actin cytoskeleton, higher vinculin expression) for 2D and 3D scaffolds
• Mono-culturing of hepatocytes lead to loss of hepatic morphology and reduced albumin secretion
• Formation of long-term hepatocyte colonies when co-cultured with fibroblasts
• High CYP450 A1 enzyme activity for 3D co-culture model

Conclusion: The development of a well-differentiated 3D hepatocyte co-culture as a relatively stable liver model was successful. Morphology and function of 3D co-cultured hepatocytes on fibronectin-coated chitosan nanofibers was maintained. The 3D liver model could be a helpful tool for screening of drugs and evaluation of drug intake and metabolism.

Source: http://onlinelibrary.wiley.com/wol1/doi/10.1002/jbm.a.36072/full

Another study investigated how material and processing parameters affect the electrospun morphology of chitosan nanofibers.

Nanofibrous morphology of electrospun chitosan nanocomposites reinforced with WS2 nanotubes: A design-of-experiments study

Baklavaridis, I. Zuburtikudis and C. Panayiotou. Journal of industrial textiles. 1-27. DOI: 10.1177/1528083717725114

The researchers prepared chitosan nanofibers combined with tungsten disulfide inorganic nanotubes (INT-WS₂). The influence on morphology of chitosan nanofiber mats by solution concentration, dynamic viscosity, density, surface tension, dielectric permittivity, and electrical conductivity was investigated. Furthermore, process parameters like electric field, diameter and angle of the spinneret, the spinning distance and the flow rate. In the study, Chitosan (95/500) by Heppe Medical Chitosan GmbH was used to create chitosan nanocomposite electrospun mats. Morphological characterization by scanning electron microscopy and statistical analysis were conducted.

RESULTS

• Solution concentration, electrical field strength and INT-WS₂ loading significantly influence morphology
• Addition of INT-WS₂ enhances bead formation on the nanofibrous structure
• Morphology is linked to the number surface density of the beads, the average bead-to-fiber diameter and the fiber thickness

Conclusion: Desired nanofibrous chitosan/INT-WS₂ morphology can be tuned by electrospinning parameters.

Source: http://journals.sagepub.com/doi/10.1177/1528083717725114