Cell-Derived Polymer/Extracellular Matrix Composite Scaffolds for Cartilage Regeneration, Part 1: Investigation of Cocultures and Seeding Densities for Improved Extracellular Matrix Deposition

Abstract

This study investigated the coculture of chondrocytes and mesenchymal stem cells (MSCs) on electrospun fibrous polymer scaffolds to produce polymer/extracellular matrix (ECM) hybrid constructs with the objective of reducing the number of chondrocytes necessary to produce ample cartilage-like ECM within the scaffolds. To generate these hybrid constructs, electrospun poly(e-caprolactone) fibrous scaffolds were seeded at both high and low initial densities with five different ratios of chondrocytes to MSCs: 1:0, 1:1, 1:3, 1:5, and 0:1, and cultured for 7, 14, and 21 days. Glycosaminoglycan production and distribution within the three coculture groups was similar to quantities generated by chondrocyte-only controls. Conversely, as the concentration of chondrocytes was increased, the collagen content of the constructs also increased at each time point, with a 1:1 chondrocyte to MSC ratio approximating the collagen production of chondrocytes alone. Histological staining suggested that cocultured constructs mimicked the well-distributed ECM patterns of chondrocyte generated constructs, while improving greatly over the restricted distribution of matrix within MSC-only constructs. These results support the capacity of cocultures of chondrocytes and MSCs to generate cartilaginous matrix within a polymeric scaffold. Further, the inclusion of MSCs in these cocultures enables the reduction of chondrocytes needed to produce cell-generated ECM.

Direct and indirect co-culture of chondrocytes and mesenchymal stem cells for the generation of polymer/extracellular matrix hybrid constructs

“…Non-woven fibrous poly(∊ -caprolactone) (PCL) scaffolds were fabricated by electrospinning using previously described methods [15]. 18% (w/w) PCL was first dissolved in a 5:1 (v/v) solution of chloroform: methanol and expelled at a flowrate of 25 mL/hr into an electric field formed by a voltage source with 30 kV applied voltage.…”

“…One such method is by utilizing co-cultures of chondrocytes and MSCs to generate similar quantities of cartilage-like ECM as cultures of chondrocytes alone [15, 16]. Various studies have shown that co-culturing MSCs with chondrocytes leads to increased chondrogenic gene expression and ECM deposition when cultured both in direct cell-cell contact or separated by a barrier, such as a Transwell® membrane, or in conditioned media systems [17-21].…”

“…Many studies confirm the secretion of cytokines and growth factors from MSCs exhibiting anti-inflammatory effects in addition to an increase in matrix production by chondrocytes [23-25] while some studies have elucidated positive chondroinduction of MSCs co-cultured with chondrocytes shown to produce growth factors, MMPs, and parathyroid hormone related protein [20, 26, 27]. Previous work showed that a 1:1 ratio of chondrocytes to MSCs was capable of producing similar quantities of cartilage-like ECM as cultures of chondrocytes alone and that the ECM exhibited a similar chondroinductive effect on MSCs as polymer/ECM scaffolds generated using cultures of chondrocytes [15, 28]. …”

Optimization of Polymer-ECM Composite Scaffolds for Tissue Engineering: Effect of Cells and Culture Conditions on Polymeric Nanofiber Mats

“…This requires the polymer to have functionalizable pendant chains or end groups [29]. A less common, but increasingly investigated approach is to use cells to deposit their native ECM onto the scaffold, followed by decellularization and the use of this ECM-polymer composite scaffold as a bioactive support for subsequent recellularization [33,34,35]. This approach (which we refer to as the cellularization-decell-recell cycle) harnesses the naturally-occurring bioactive signals from a selected cell source to modify the biological responses of subsequently seeded cell populations.…”

Multifunctional ECM proteins in bone and teeth

“…Briefly, the ECM determines tissue functionality. Recent tissue engineering strategies have focused on mimicking the composition of the ECM to achieve desired cellular behavior and lineage specific differentiation to facilitate regeneration of tissues such as bone, dental pulp and cartilage (2–5). The primary reason behind such approaches lies in the complex nature of the ECM.…”