Alginate – chitosan – alginate multilayer hydrogel encapsulation systems were investigated for

encapsulation of chondrocytes. Hydrogel is crosslinked due to ionic interaction between cationic

chitosan and anionic alginate, and additionally by calcium ions. Two types of chitosan with

molecular weight were investigated. Cells were encapsulated in two shape microcapsules, microbeads with diameter size 300 – 400 and 500 - 600 µm and fibres with diameter 500 - 600 µm. The

work provides a detailed examination of the impact of the microencapsulation process on the growth

of cells. The viability of chondrocytes can be influenced by the size of produced microcapsules,

while the shape of microcapsules has no important significance on cell viability. The applied

encapsulation methods do not contain harmful stages and create conducive conditions for cell

growth. A possible application area of the developed system is dressing and regeneration of

damaged joint cartilage.

B a c k g r o u n d: Articular cartilage is highly-organized nonvascularized tissue which is responsible in humans for pressure absorption under load, as well as for the smoothness of the opposite tangential bone surfaces.

The purpose of our research is to study structural and functional features of articular cartilage at lightoptical level by using state-of-the-art research methods of bone-cartilage tissue.

M a t e r i a l a n d M e t h o d s: The study was conducted on samples of femoral heads. Hyperfine sections were subject to hematoxylin and eosin, Van Gieson’s and PAS staining. In order to identify the receptor profile of chondrocytes and the features of protein arrangement in extracellular matrix we undertook an immunohistochemical study.

R e s u l t s: An articular cartilage is quite organized tissue. As any other organ, it has parenchyma and stroma. Parenchyma is represented by one type of cells — chondrocytes, which, depending on how deep they are located in cartilage, have a different shape, size and functional features. The chondrocytes and extracellular matrix have different degrees of receptors expression.

C o n c l u s i o n s: Th e cartilage is being constantly self-renewed, what is manifested by means of a rather slow division of the surface-located chondrocytes and programmed death of dystrophic-modified cells. The features of extracellular matrix structure determine the originality of cell location in different areas of cartilage tissue. Due to synthesis of specific proteins, chondrocytes self-regulate properties of cartilage tissue.

One of the actual challenges in tissue engineering applications is to efficiently produce as high of number of cells as it is only possible, in the shortest time. In static cultures, the production of animal cell biomass in integrated forms (i.e. aggregates, inoculated scaffolds) is limited due to inefficient diffusion of culture medium components observed in such non-mixed culture systems, especially in the case of cell-inoculated fiber-based dense 3D scaffolds, inside which the intensification of mass transfer is particularly important. The applicability of a prototyped, small-scale, continuously wave-induced agitated system for intensification of anchorage-dependent CP5 chondrocytes proliferation outside and inside three-dimensional poly(lactic acid) (PLA) scaffolds has been discussed. Fibrous PLA-based constructs have been inoculated with CP5 cells and then maintained in two independent incubation systems: (i) non-agitated conditions and (ii) culture with wave-induced agitation. Significantly higher values of the volumetric glucose consumption rate have been noted for the system with the wave-induced agitation. The advantage of the presented wave-induced agitation culture system has been confirmed by lower activity of lactate dehydrogenase (LDH) released from the cells in the samples of culture medium harvested from the agitated cultures, in contrast to rather high values of LDH activity measured for static conditions. Results of the proceeded experiments and their analysis clearly exhibited the feasibility of the culture system supported with continuously wave-induced agitation for robust proliferation of the CP5 chondrocytes on PLA-based structures. Aside from the practicability of the prototyped system, we believe that it could also be applied as a standard method offering advantages for all types of the daily routine laboratory-scale animal cell cultures utilizing various fiber-based biomaterials, with the use of only regular laboratory devices.