Lipoplex-Functionalized Thin-Film Surface Coating Based on Extracellular Matrix Components as Local Gene Delivery System to Control Osteogenic Stem Cell Differentiation

The development of smart multifunctional biomaterials with the ability to control the behavior of stem cells on demand has become a powerful strategy in regenerative medicine and cell therapies.*

Stem cell-based therapies for example can offer possibilities to regenerate critical size bone defects from severe fractures or bone tissue loss after surgery. *

Various studies have determined characteristics and modifications of biomaterials that enable initiation of stem cell osteogenesis and represent promising approaches for clinical use. These approaches include materials that can mimic the bone microenvironment, materials with specific mechanical properties which stimulate bone tissue formation, and materials which can release or control the activity of osteoinductive growth factors. *

A straightforward strategy for the functionalization of biomaterials involves emulating the properties of the extracellular matrix (ECM) for the formation of an artificial microenvironment that enables a precise control of cell behavior and function. *

Due to interaction of ECM components with cell surface receptors such as integrins, ECM regulates cell proliferation, migration, and differentiation.*

Therefore, the development of surface coatings mimicking the native ECM structure and function is of considerable interest to functionalize implant materials. *

The layer-by-layer (LbL) technology, well-known from the pioneering work by Decher et al. on the development of polyelectrolyte multilayers (PEMs) on solid surfaces by alternating deposition of oppositely charged polyelectrolytes, has evolved into a very simple and cost effective yet highly versatile and efficient surface modification and functionalization technology.*

The LbL technique allows the production of multifunctional thin film coatings with precise control of the film composition, structure, properties, and functions at the nanoscale. *

A further advantage of LbL is that it can be performed by different methods such as dip-coating, spray coating, and spin-coating protocols allowing the coating of different materials and designs also in a time-saving manner.*

Indeed, polyelectrolyte multilayers (PEMs) have been broadly used as reservoir for either the surface immobilization or encapsulation of bioactive molecules, more precisely drugs and proteins, to engineer bio-functional materials by choice of polyelectrolytes and complexation conditions for regenerative medicine strategies.*

Previous studies have consistently demonstrated that electrostatic-driven LbL assembly is a powerful and simple technique to functionalize biomaterials with nucleic acids aiming for non-viral gene delivery. *

In the article “Lipoplex-Functionalized Thin-Film Surface Coating Based on Extracellular Matrix Components as Local Gene Delivery System to Control Osteogenic Stem Cell Differentiation” Catharina Husteden, Yazmin A. Brito Barrera, Sophia Tegtmeyer, João Borges, Julia Giselbrecht, Matthias Menzel, Andreas Langner, João F. Mano, Christian E. H. Schmelzer, Christian Wölk and Thomas Groth describe how they combined both approaches, such as the ECM-mimicking character of PEM and their ability to be used as carrier for in situ transfection, to develop a gene-activated ECM-mimicking surface coating to direct stem cells’ fate.*

They focused on a bone ECM-mimicking PEMs consisting of Col and Cs loaded with LPX composed of OO4/DOPE lipid composite. *

Furthermore, they studied the ability of the system to induce osteogenic stem cell differentiation by gene expression analysis and mineralization assays. *

The authors present a new approach to engineer a bone-ECM inspired gene-activated surface coating which allows controlling stem cells function, and consequently, represents a promising tool to develop multifunctional surface coatings for regenerative medicine strategies. *

Atomic Force Microscopy (AFM) was used to study the topography and the mechanical properties of the different polyelectrolyte multilayers (PEMs). *

In order to investigate the elasticity and the force curve, the samples were compressed by the AFM tip and the force mapping mode was applied while the AFM tip scanned a specific area of the sample. *

The force mapping mode measured the interaction forces such as adhesion or electrostatics and gives an idea regarding the stiffness and topography. The interest in testing mechanical properties and topography of surface coatings is related to their effect on cell behavior, such as spreading, proliferation, and differentiation. *

Atomic force microscopy with a commercially available AFM instrument in combination with an inverted fluorescence microscope was performed in quantitative imaging mode (QI^TM1) to investigate the surface roughness and topography as well as record corresponding fluorescence images. *

The topographical images were recorded using NANOSENSORS^TM uniqprobe qp-BioT AFM cantilevers in a standard liquid cell containing 0.15 m NaCl solution.  The uniqprobe qp-BioT AFM probe types with their two different triangular AFM cantilevers (Cantilever Beam 1 (CB1) typical resonant frequency 50 kHz, typical force constant 0.3 N/m, Cantilever Beam 2 (CB2): typical resonant frequency 20 kHz, typical force constant 0.08 N/m ) offer an alternative to silicon nitride AFM probes, with the advantage of reduced thermal drift and taller AFM tips with smaller opening angles. *

A force map area of 5 × 5 µm2 was recorded with a resolution of 512 × 512 pixel2.

*Catharina Husteden, Yazmin A. Brito Barrera, Sophia Tegtmeyer, João Borges, Julia Giselbrecht, Matthias Menzel, Andreas Langner, João F. Mano, Christian E. H. Schmelzer, Christian Wölk and Thomas Groth
Lipoplex-Functionalized Thin-Film Surface Coating Based on Extracellular Matrix Components as Local Gene Delivery System to Control Osteogenic Stem Cell Differentiation
Advanced Healthcare Materials, Volume 12, Issue, February 17, 2023, 2201978
DOI: https://doi.org/10.1002/adhm.202201978

Open Access: The article “Lipoplex-Functionalized Thin-Film Surface Coating Based on Extracellular Matrix Components as Local Gene Delivery System to Control Osteogenic Stem Cell Differentiation” by Catharina Husteden, Yazmin A. Brito Barrera, Sophia Tegtmeyer, João Borges, Julia Giselbrecht, Matthias Menzel, Andreas Langner, João F. Mano, Christian E. H. Schmelzer, Christian Wölk and Thomas Groth is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.

¹QI^TM mode is a trademark of Bruker Nano GmbH