Imaging Cell Interactions With Native and Crosslinked Polyelectrolyte Multilayers

Abstract

The adhesion of primary chondrocytes to polyelectrolyte multilayer films, made of poly(l-lysine) (PLL) and hyaluronan (HA), was investigated for native and crosslinked films, either ending by PLL or HA. Crosslinking the film was achieved by means of a water-soluble carbodiimide in combination with N-hydroxysulfosuccinimide. The adhesion of macrophages and primary chondrocytes was investigated by microscopical techniques (optical, confocal, and atomic), providing useful information on the cell/film interface. Native films were found to be nonadhesive for the primary chondrocytes, but could be degraded by macrophages, as could be visualized by confocal laser scanning microscopy after film labeling. Confocal microscopy images show that these films can be deformed by the chondrocytes and that PLL diffuses at the chondrocyte membrane. In contrast, the cells adhered and proliferated well on the crosslinked films, which were not degraded by the macrophages. These results were confirmed by a MTT test over a 6-d period and by atomic force microscopy observations. We thus prove that chemical crosslinking can dramatically change cell adhesion properties, the cells being more stably anchored on the crosslinked films.

Polyelectrolyte Multilayer Films of Controlled Stiffness Modulate Myoblast Cell Differentiation

“…The present findings highlight, in particular, the important role of the surface mechanical properties in cell/material interactions. As the polyelectrolyte multilayer films of controlled stiffness can also be loaded with bioactive molecules [54] and present the advantages of being non-toxic, biocompatible and biodegradable [55] , they could be further be employed as "multi-functional" films to investigate the respective roles of stiffness versus bioactivity and to control several key cellular processes. These PEM films could also find applications in the fields of regenerative medicine and muscle/cardiac tissue engineering, where controlling the cell/material interactions is crucial for guiding the cellular response.…”

Multiple Functionalities of Polyelectrolyte Multilayer Films: New Biomedical Applications

“…[134] Interestingly, chondrosarcoma cells, initially poorly adherent on native PEM, adhered, spread, and proliferated on the cross-linked films, with a strong dependence of all these parameters on the cross-linking extent. This adhesion ''switch'' appeared to be a property common to many film types, including PLL/HA, [128,130,196,197] CHI/HA, [198] PLL/PGA, [110,199] and PLL/poly-(galacturonic acid). [199] This change in adhesive properties was observed for a wide variety of cell types, including chondrocytes, [196] chondrosarcomas, [110] macrophages, [132,196] neurons, [196] osteoblasts, [199] SMCs, [130] and skeletal muscle cells.…”

Polyelectrolyte Multilayers in Tissue Engineering

“…For PEMs with the appropriate functional chemistry, such as amine and/or carboxyl groups, water-based covalent chemical crosslink chemistries have been investigated. 16,32,[69][70][71] Carbodiimide crosslinkers such as 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (commonly referred to as EDC) are crosslinkers used to couple carboxyl and amine groups leading to the formation of amide bonds. 70,[72][73][74] In a recent study, the Young's modulus was varied for PLL/HA PEMs to modulate myoblast adhesion, differentiation, and myotube formation using EDC concentrations ranging from 5 to 100 mg/mL.…”

“…20 For most cell types, increased substrate stiffness promotes cellular adhesion. 16,29,38,53,55,56,62,69 The range of mechanical properties in PEMs due to assembly conditions can be used to probe cellular mechanics as well as promote cellular functions for tissue engineering (Table 1).…”