Publications in July & August 2014

In the summer month July and August 2014, 246 articles about chitosan and chitosan derivatives have been published. These articles were mainly published by scientists from China (59 articles), USA (31) and India (30). The top terms in this month addressed nanoparticles, pharmaceutical preparations and animal studies.

Table: Leading scientific journals, publishing most chitosan-related articles in July and August 2014.
Source: GoPubMed

Natural polymers like chitosan, alginate and collagen are of great interest in the tissue-engineering field.  As they are derived from living organisms, these biomaterials are biodegradable, non-toxic and can promote cell attachment and growth. In July and August 18 articles were published about chitosan-modified biopolymers. Below, two astonishing publications are presented in detail.

A simple material model to generate epidermal and dermal layers in vitro for skin regeneration.

Tsao C.T., Leung M., Chang J.Y., Zhang M.; Journal of materials chemistry. B, Materials for biology and medicine. Vol. 2 (32): 5256-5264; August 2014

The development of cellularized skin grafts is a highly promising technology in the treatment of severe skin defects like chronic wounds or skin burns. The authors of this study developed a bi-layered skin equivalent based on chitosan and analyzed different graft compositions in terms of cell proliferation rate and cell maturation within the wounds.

The graft core was composed of porous chitosan-alginate (CA), which provided mechanical support. The CA-scaffold was impregnated with a thermally reversible gel of chitosan poly(ethylene glyocol) (C-PEG). The gel was designed to encapsulate fibroblasts and represented the dermal skin layer. The epidermis layer was created by keratinocytes, seeded to the CA/C-PEG surface. Three different experimental conditions were tested.

Fig. a: CA-grafts without C PEG gel, cultured in cell media Fig. b: CA/C-PEG-grafts placed in media without an air liquid interface Fig. c: CA/C-PEG-grafts with an air-liquid interface

Results:

• CA/C-PEG-grafts enhance cell proliferation of keratinocytes and fibroblasts
• The air-liquid interface promotes maturation of keratinocytes 
• CA/C-PEG-grafts mimic skin microenvironment

Source: http://www.ncbi.nlm.nih.gov/pubmed/25147728

Comparison of biomaterial delivery vehicles for improving acute retention of stem cells in the infarcted heart.

Roche E.T., Hastings C.L., Lewin S.A. et al.; Biomaterials. Vol. 35 (25): 6850-8, August 2014.

A myocardial infarction (heart attack; MI) is a live threatening event, which is caused by local circulation disorders of the heart muscle. Since MI is a leading cause of death worldwide, new approaches of treatment are urgently needed.

The aim of this study was to compare different natural polymers (chitosan, alginate, collagen) in terms of promoting viability, delivery and retainment of inserted cells. Human mesenchymal stem cells (hMSCs) were incorporated into injectable hydrogels, made of chitosan/β-glycerophosphate or alginate. hMSCs were further loaded to epicardial patches of alginate or collagen. Cells solved in saline solution represents the current clinical standard and served as reference.

Results:

• In vitro: Cell viability was diminished in all biomaterials upon hypoxic condition (mimic infarct environment), but was still higher compared to monolayer cultures.
• In vivo: Experiments were conducted in a rat myocardial infarct model. hMSCs loaded samples were placed into the infarct border zone. The cell retainment was determined after 24 h by fluorescence imaging (GFP-hMSCs) and immunohistochemical analysis.

(*)   x-fold increase over saline solution

Conclusion: All tested polymers, including chitosan, improved cell viability, delivery and retainment compared to standard cell-loaded saline solution. The positive features of the analyzed biomaterials make them suitable for in vivo cell-delivery systems.