A porous PCL scaffold promotes the human chondrocytes redifferentiation and hyaline-specific extracellular matrix protein synthesis

Biocompatibility and dimensional stability through the use of 3D-printed scaffolds made by polycaprolactone and bioglass-7: An in vitro and in vivo study

PURPOSE

This experiment aimed to observe the differences in biological properties by producing BGS-7 + PCL scaffolds with different weight fractions of BGS-7 through 3D printing and to confirm whether using the scaffold for vertical bone augmentation is effective.

MATERIALS AND METHODS

Cube-shaped bioglass (BGS-7) and polycaprolactone (PCL) scaffolds with different weight fractions (PCL alone, PCL with 15% and 30% BGS-7) are produced using 3D printing. The surface hydroxyapatite (HA) apposition, the pH change, proliferation and attachment assays, and various gene expression levels are assessed. After a 7-mm implant was inserted 3 mm into the rabbit calvaria, vertical bone augmentation is performed around the implant and inside the scaffold in four ways: scaffold only, scaffold+bone graft, bone graft only, and no graft. Sacrifice is performed at 6, 12, and 24 weeks, and the various parameters are compared radiographically and histologically.

RESULTS

HA apposition, cell proliferation, cell attachment, and expression of osteogenic genes increase as the proportion of BGS-7 increase. In the in vivo test, a higher bone-implant contact ratio, bone volume ratio, bone mineral density, and new bone area are observed when the scaffold and bone grafts were used together.

CONCLUSION

The 3D-printed scaffold, a mixture of BGS-7 and PCL, exhibit higher biological compatibility as the proportion of BGS-7 increase. Additionally, the use of scaffold is effective for vertical bone augmentation.

Thermosensitive and biodegradable PCL-based hydrogels: potential scaffolds for cartilage tissue engineering

Due to a lack of sufficient blood supply and unique physicochemical properties, the treatment of injured cartilage is laborious and needs an efficient strategy. Unfortunately, most of the current therapeutic approaches are, but not completely, unable to restore the function of injured cartilage. Tissue engineering-based modalities are an alternative option to reconstruct the injured tissue. Considering the unique structure and consistency of cartilage tissue (osteochondral junction), it is mandatory to apply distinct biomaterials with unique properties slightly different from scaffolds used for soft tissues. PCL is extensively used for the fabrication of fine therapeutic scaffolds to accelerate the restorative process. Thermosensitive PCL hydrogels with distinct chemical compositions have paved the way for sophisticated cartilage regeneration. This review aimed to collect recent findings regarding the application of PCL in hydrogels blended with natural, synthetic materials in the context of cartilage healing.

Novel 3D Bioglass Scaffolds for Bone Tissue Regeneration

The design of scaffolds with optimal biomechanical properties for load-bearing applications is an important topic of research. Most studies have addressed this problem by focusing on the material composition and not on the coupled effect between the material composition and the scaffold architecture. Polymer-bioglass scaffolds have been investigated due to the excellent bioactivity properties of bioglass, which release ions that activate osteogenesis. However, material preparation methods usually require the use of organic solvents that induce surface modifications on the bioglass particles, compromising the adhesion with the polymeric material thus compromising mechanical properties. In this paper, we used a simple melt blending approach to produce polycaprolactone/bioglass pellets to construct scaffolds with pore size gradient. The results show that the addition of bioglass particles improved the mechanical properties of the scaffolds and, due to the selected architecture, all scaffolds presented mechanical properties in the cortical bone region. Moreover, the addition of bioglass indicated a positive long-term effect on the biological performance of the scaffolds. The pore size gradient also induced a cell spreading gradient.

Freeze-Dried Curdlan/Whey Protein Isolate-Based Biomaterial as Promising Scaffold for Matrix-Associated Autologous Chondrocyte Transplantation-A Pilot In-Vitro Study

The purpose of this pilot study was to establish whether a novel freeze-dried curdlan/whey protein isolate-based biomaterial may be taken into consideration as a potential scaffold for matrix-associated autologous chondrocyte transplantation. For this reason, this biomaterial was initially characterized by the visualization of its micro- and macrostructures as well as evaluation of its mechanical stability, and its ability to undergo enzymatic degradation in vitro. Subsequently, the cytocompatibility of the biomaterial towards human chondrocytes (isolated from an orthopaedic patient) was assessed. It was demonstrated that the novel freeze-dried curdlan/whey protein isolate-based biomaterial possessed a porous structure and a Young's modulus close to those of the superficial and middle zones of cartilage. It also exhibited controllable degradability in collagenase II solution over nine weeks. Most importantly, this biomaterial supported the viability and proliferation of human chondrocytes, which maintained their characteristic phenotype. Moreover, quantitative reverse transcription PCR analysis and confocal microscope observations revealed that the biomaterial may protect chondrocytes from dedifferentiation towards fibroblast-like cells during 12-day culture. Thus, in conclusion, this pilot study demonstrated that novel freeze-dried curdlan/whey protein isolate-based biomaterial may be considered as a potential scaffold for matrix-associated autologous chondrocyte transplantation.

Dual crosslinked pullulan-gelatin cryogel scaffold for chondrocyte-mediated cartilage repair: synthesis, characterization andin vitroevaluation

Cryogels, a subset of hydrogels, have recently drawn attention for cartilage tissue engineering due to its inherent microporous architecture and good mechanical properties. In this study a dual crosslinked pullulan-gelatin cryogel (PDAG) scaffold was synthesized by crosslinking gelatin with oxidized pullulan by Schiff's base reaction followed by cryogelation. Chondrocytes seeded within the PDAG scaffolds and cultured for 21 din vitrodemonstrated enhanced cell proliferation, enhanced production of cartilage-specific extracellular matrix and up-regulated sulfated glycosaminoglycan without altering the articular chondrocyte phenotype. Quantitative reverse transcription-polymerase chain reaction-based gene expression studies, immunofluorescence, and histological studies demonstrated that the PDAG scaffold significantly enhanced the expression of chondrogenic marker genes such as type II collagen, aggrecan, and SOX9. Taken together, these results demonstrated that PDAG scaffold prepared by sequential Schiff's base reaction and cryogelation would be a promising cell-responsive scaffold for cartilage tissue engineering applications.

Fabrication of 3D plotted scaffold with microporous strands for bone tissue engineering

Scaffold porosity has played a key role in bone tissue engineering aimed at effective tissue regeneration, by promoting cell attachment, proliferation, and osteogenic differentiation for new bone formation.

Evaluation of Polycaprolactone-Associated Human Nasal Chondrocytes as a Therapeutic Agent for Cartilage Repair

Background

In this study, we manufactured a complex of human nasal septal cartilage (hNC) with polycaprolactone (PCL) for transplantation into cartilaginous skeletal defects and evaluated their characteristics.

Methods

Nasal septum tissue was obtained from five patients aged ≥ 20 years who were undergoing septoplasty. hNCs were isolated and subcultured for three passages in vitro. To formulate the cell-PCL complex, we used type I collagen as an adhesive between chondrocyte and PCL. Immunofluorescence staining, cell viability and growth in the hNC-PCL complex, and mycoplasma contamination were assessed.

Results

hNCs in PCL showed viability ≥ 70% and remained at these levels for 9 h of incubation at 4 °C. Immunostaining of the hNC-PCL complex also showed high expression levels of chondrocyte-specific protein, COL2A1, SOX9, and aggrecan during 24 h of clinically applicable conditions.

Conclusion

The hNC-PCL complex may be a valuable therapeutic agent for implantation into injured cartilage tissue, and can be used clinically to repair cartilaginous skeletal defects. From a clinical perspective, it is important to set the short duration of the implantation process to achieve effective functional implantation.

Differential chondro- and osteo-stimulation in three-dimensional porous scaffolds with different topological surfaces provides a design strategy for biphasic osteochondral engineering

Bone/cartilage interfacial tissue engineering needs to satisfy the differential properties and architectures of the osteochondral region. Therefore, biphasic or multiphasic scaffolds that aim to mimic the gradient hierarchy are widely used. Here, we find that two differently structured (topographically) three-dimensional scaffolds, namely, "dense" and "nanofibrous" surfaces, show differential stimulation in osteo- and chondro-responses of cells. While the nanofibrous scaffolds accelerate the osteogenesis of mesenchymal stem cells, the dense scaffolds are better in preserving the phenotypes of chondrocytes. Two types of porous scaffolds, generated by a salt-leaching method combined with a phase-separation process using the poly(lactic acid) composition, had a similar level of porosity (~90%) and pore size (~150 μm). The major difference in the surface nanostructure led to substantial changes in the surface area and water hydrophilicity (nanofibrous ≫ dense); as a result, the nanofibrous scaffolds increased the cell-to-matrix adhesion of mesenchymal stem cells significantly while decreasing the cell-to-cell contracts. Importantly, the chondrocytes, when cultured on nanofibrous scaffolds, were prone to lose their phenotype, including reduced chondrogenic expressions (SOX-9, collagen type II, and Aggrecan) and glycosaminoglycan content, which was ascribed to the enhanced cell-matrix adhesion with reduced cell-cell contacts. On the contrary, the osteogenesis of mesenchymal stem cells was significantly accelerated by the improved cell-to-matrix adhesion, as evidenced in the enhanced osteogenic expressions (RUNX2, bone sialoprotein, and osteopontin) and cellular mineralization. Based on these findings, we consider that the dense scaffold is preferentially used for the chondral-part, whereas the nanofibrous structure is suitable for osteo-part, to provide an optimal biphasic matrix environment for osteochondral tissue engineering.

Peptide-Based Materials for Cartilage Tissue Regeneration

Cartilaginous tissue requires structural and metabolic support after traumatic or chronic injuries because of its limited capacity for regeneration. However, current techniques for cartilage regeneration are either invasive or ineffective for long-term repair. Developing alternative approaches to regenerate cartilage tissue is needed. Therefore, versatile scaffolds formed by biomaterials are promising tools for cartilage regeneration. Bioactive scaffolds further enhance the utility in a broad range of applications including the treatment of major cartilage defects. This chapter provides an overview of cartilage tissue, tissue defects, and the methods used for regeneration, with emphasis on peptide scaffold materials that can be used to supplement or replace current medical treatment options.

Dedifferentiated Human Articular Chondrocytes Redifferentiate to a Cartilage-Like Tissue Phenotype in a Poly(ε-Caprolactone)/Self-Assembling Peptide Composite Scaffold

Adult articular cartilage has a limited capacity for growth and regeneration and, with injury, new cellular or biomaterial-based therapeutic platforms are required to promote repair. Tissue engineering aims to produce cartilage-like tissues that recreate the complex mechanical and biological properties found in vivo. In this study, a unique composite scaffold was developed by infiltrating a three-dimensional (3D) woven microfiber poly (ε-caprolactone) (PCL) scaffold with the RAD16-I self-assembling nanofibers to obtain multi-scale functional and biomimetic tissue-engineered constructs. The scaffold was seeded with expanded dedifferentiated human articular chondrocytes and cultured for four weeks in control and chondrogenic growth conditions. The composite constructs were compared to control constructs obtained by culturing cells with 3D woven PCL scaffolds or RAD16-I independently. High viability and homogeneous cell distribution were observed in all three scaffolds used during the term of the culture. Moreover, gene and protein expression profiles revealed that chondrogenic markers were favored in the presence of RAD16-I peptide (PCL/RAD composite or alone) under chondrogenic induction conditions. Further, constructs displayed positive staining for toluidine blue, indicating the presence of synthesized proteoglycans. Finally, mechanical testing showed that constructs containing the PCL scaffold maintained the initial shape and viscoelastic behavior throughout the culture period, while constructs with RAD16-I scaffold alone contracted during culture time into a stiffer and compacted structure. Altogether, these results suggest that this new composite scaffold provides important mechanical requirements for a cartilage replacement, while providing a biomimetic microenvironment to re-establish the chondrogenic phenotype of human expanded articular chondrocytes.

Thermogel-Coated Poly(ε-Caprolactone) Composite Scaffold for Enhanced Cartilage Tissue Engineering

A three-dimensional (3D) composite scaffold was prepared for enhanced cartilage tissue engineering, which was composed of a poly(ε-caprolactone) (PCL) backbone network and a poly(lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly(lactide-co-glycolide) (PLGA⁻PEG⁻PLGA) thermogel surface. The composite scaffold not only possessed adequate mechanical strength similar to native osteochondral tissue as a benefit of the PCL backbone, but also maintained cell-friendly microenvironment of the hydrogel. The PCL network with homogeneously-controlled pore size and total pore interconnectivity was fabricated by fused deposition modeling (FDM), and was impregnated into the PLGA⁻PEG⁻PLGA solution at low temperature (e.g., 4 °C). The PCL/Gel composite scaffold was obtained after gelation induced by incubation at body temperature (i.e., 37 °C). The composite scaffold showed a greater number of cell retention and proliferation in comparison to the PCL platform. In addition, the composite scaffold promoted the encapsulated mesenchymal stromal cells (MSCs) to differentiate chondrogenically with a greater amount of cartilage-specific matrix production compared to the PCL scaffold or thermogel. Therefore, the 3D PCL/Gel composite scaffold may exhibit great potential for in vivo cartilage regeneration.

Differentiation of mesenchymal stem cells for cartilage tissue engineering: Individual and synergetic effects of three-dimensional environment and mechanical loading

Chondrogenesis of dedifferentiated chondrocytes and mesenchymal stem cells is influenced not only by soluble molecules like growth factors, but also by the cell environment itself. The latter is achieved through both mechanical cues - which act as stimulation factor and influences nutrient transport - and adhesion to extracellular matrix cues - which determine cell shape. Although the effects of soluble molecules and cell environment have been intensively addressed, few observations and conclusions about the interaction between the two have been achieved. In this work, we review the state of the art on the single effects between mechanical and biochemical cues, as well as on the combination of the two. Furthermore, we provide a discussion on the techniques currently used to determine the mechanical properties of materials and tissues generated in vitro, their limitations and the future research needs to properly address the identified problems.

STATEMENT OF SIGNIFICANCE

The importance of biomechanical cues in chondrogenesis is well known. This paper reviews the existing literature on the effect of mechanical stimulation on chondrogenic differentiation of mesenchymal stem cells in order to regenerate hyaline cartilage. Contradictory results found with respect to the effect of different modes of external loading can be explained by the different properties of the scaffolding system that holds the cells, which determine cell adhesion and morphology and spatial distribution of cells, as well as the stress transmission to the cells. Thus, this review seeks to provide an insight into the interplay between external loading program and scaffold properties during chondrogenic differentiation. The review of the literature reveals an important gap in the knowledge in this field and encourages new experimental studies. The main issue is that in each of the few cases in which the interplay is investigated, just two groups of scaffolds are compared, leaving intermediate adhesion conditions out of study. The authors propose broader studies implementing new high-throughput techniques for mechanical characterization of tissue engineering constructs and the inclusion of fatigue analysis as support methodology to more exhaustive mechanical characterization.

Biodegradable CSMA/PECA/Graphene Porous Hybrid Scaffold for Cartilage Tissue Engineering

Owing to the limited repair capacity of articular cartilage, it is essential to develop tissue-engineered cartilage for patients suffering from joint disease and trauma. Herein, we prepared a novel hybrid scaffold composed of methacrylated chondroitin sulfate (CSMA), poly(ethylene glycol) methyl ether-ε-caprolactone-acryloyl chloride (MPEG-PCL-AC, PECA was used as abbreviation for MPEG-PCL-AC) and graphene oxide (GO) and evaluated its potential application in cartilage tissue engineering. To mimic the natural extracellular matrix (ECM) of cartilage, the scaffold had an adequate pore size, porosity, swelling ability, compression modulus and conductivity. Cartilage cells contacted with the scaffold remained viable and showed growth potential. Furthermore, CSMA/PECA/GO scaffold was biocompatible and had a favorable degradation rate. In the cartilage tissue repair of rabbit, Micro-CT and histology observation showed the group of CSMA/PECA/GO scaffold with cellular supplementation had better chondrocyte morphology, integration, continuous subchondral bone, and much thicker newly formed cartilage compared with scaffold group and control group. Our results show that the CSMA/PECA/GO hybrid porous scaffold can be applied in articular cartilage tissue engineering and may have great potential to in other types of tissue engineering applications.

Surface modification of polycaprolactone scaffolds fabricated via selective laser sintering for cartilage tissue engineering

Surface modified porous polycaprolactone scaffolds fabricated via rapid prototyping techniques were evaluated for cartilage tissue engineering purposes. Polycaprolactone scaffolds manufactured by selective laser sintering (SLS) were surface modified through immersion coating with either gelatin or collagen. Three groups of scaffolds were created and compared for both mechanical and biological properties. Surface modification with collagen or gelatin improved the hydrophilicity, water uptake and mechanical strength of the pristine scaffold. From microscopic observations and biochemical analysis, collagen-modified scaffold was the best for cartilage tissue engineering in terms of cell proliferation and extracellular matrix production. Chondrocytes/collagen-modified scaffold constructs were implanted subdermally in the dorsal spaces of female nude mice. Histological and immunohistochemical staining of the retrieved implants after 8 weeks revealed enhanced cartilage tissue formation. We conclude that collagen surface modification through immersion coating on SLS-manufactured scaffolds is a feasible scaffold for cartilage tissue engineering in craniofacial reconstruction.

Three-dimensional scaffold-free fusion culture: the way to enhance chondrogenesis of in vitro propagated human articular chondrocytes

Cartilage regeneration based on isolated and culture-expanded chondrocytes has been studied in various in vitro models, but the quality varies with respect to the morphology and the physiology of the synthesized tissues. The aim of our study was to promote in vitro chondrogenesis of human articular chondrocytes using a novel three-dimensional (3-D) cultivation system in combination with the chondrogenic differentiation factors transforming growth factor beta 2 (TGF-b2) and L-ascorbic acid. Articular chondrocytes isolated from six elderly patients were expanded in monolayer culture. A single-cell suspension of the dedifferentiated chondrocytes was then added to agar-coated dishes without using any scaffold material, in the presence, or absence of TGF-b2 and/or L-ascorbic acid. Three-dimensional cartilage-like constructs, called single spheroids, and microtissues consisting of several spheroids fused together, named as fusions, were formed. Generated tissues were mainly characterized using histological and immunohistochemical techniques. The morphology of the in vitro tissues shared some similarities to native hyaline cartilage in regard to differentiated S100-positive chondrocytes within a cartilaginous matrix, with strong collagen type II expression and increased synthesis of proteoglycans. Finally, our innovative scaffold-free fusion culture technique supported enhanced chondrogenesis of human articular chondrocytes in vitro. These 3-D hyaline cartilage-like microtissues will be useful for in vitro studies of cartilage differentiation and regeneration, enabling optimization of functional tissue engineering and possibly contributing to the development of new approaches to treat traumatic cartilage defects or osteoarthritis.

Integration of scaffolds into full-thickness skin wounds: the connexin response

Scaffolds have been reported to promote healing of hard-to-heal wounds such as burns and chronic ulcers. However, there has been little investigation into the cell biology of wound edge tissues in response to the scaffolds. Here, we assess the impact of collagen scaffolds on mouse full-thickness wound re-epithelialisation during the first 5 days of healing. We find that scaffolds impede wound re-epithelialisation, inducing a bulbous thickening of the wound edge epidermis as opposed to the thin tongue of migratory keratinocytes seen in normal wound healing. Scaffolds also increase the inflammatory response and the numbers of neutrophils in and around the wound. These effects were also produced by scaffolds made of alginate in the form of fibers and microspheres, but not as an alginate hydrogel. In addition, we find the gap junction protein connexin 43, which normally down-regulates at the wound edge during re-epithelialisation, to be up-regulated in the bulbous epidermal wound edge. Incorporation of connexin 43 antisense oligodeoxynucleotides into the scaffold can be performed to reduce inflammation whilst promoting scaffold biocompatibility.

In vitro 3D culture of human chondrocytes using modified ε-caprolactone scaffolds with varying hydrophilicity and porosity

Two series of 3D scaffolds based on ε-caprolactone were synthesized. The pore size and architecture (spherical interconnected pores) was the same in all the scaffolds. In one of the series of scaffolds, made of pure ε-polycaprolactone, the volume fraction of pores varied between 60% and 85% with the main consequence of varying the interconnectivity between pores since the pore size was kept constant. The other scaffolds were prepared with copolymers made of a ε-caprolactone-based hydrophobous monomer and hydroxyethyl acrylate, as the hydrophilic component. Thus, the hydrophilicity and, presumably, the adhesion properties varied monotonously in the copolymer series while porosity was kept constant. A suspension of human chondrocytes in culture medium was injected in the 3D scaffolds and cultured in static conditions up to 28 days. SEM and immunofluorescence assays allowed characterizing cells and extracellular matrix inside the scaffolds after different culture times. To do that, cross sections of the scaffolds were observed by SEM and confocal microscopy. The quantity of cells inside the scaffolds decreases with a decrease of the volume fraction of pores, due to the lack of interconnectivity between the cavities. The scaffolds up to a 30% of hydrophilicity behave in a similar way than the hydrophobous; a further increase of the hydrophilicity rapidly decreases cell viability. In all the experiments production of collagen type I, type II, and aggrecan was found, and some cells were Ki-67 positive, showing that some cells are adhered to the pore walls and maintain their dedifferentiated phenotype even when cultured in three-dimensional conditions.

Chitosan/poly(epsilon-caprolactone) blend scaffolds for cartilage repair

Chitosan (CHT)/poly(ɛ-caprolactone) (PCL) blend 3D fiber-mesh scaffolds were studied as possible support structures for articular cartilage tissue (ACT) repair. Micro-fibers were obtained by wet-spinning of three different polymeric solutions: 100:0 (100CHT), 75:25 (75CHT) and 50:50 (50CHT) wt.% CHT/PCL, using a common solvent solution of 100 vol.% of formic acid. Scanning electron microscopy (SEM) analysis showed a homogeneous surface distribution of PCL. PCL was well dispersed throughout the CHT phase as analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The fibers were folded into cylindrical moulds and underwent a thermal treatment to obtain the scaffolds. μCT analysis revealed an adequate porosity, pore size and interconnectivity for tissue engineering applications. The PCL component led to a higher fiber surface roughness, decreased the scaffolds swelling ratio and increased their compressive mechanical properties. Biological assays were performed after culturing bovine articular chondrocytes up to 21 days. SEM analysis, live-dead and metabolic activity assays showed that cells attached, proliferated, and were metabolically active over all scaffolds formulations. Cartilaginous extracellular matrix (ECM) formation was observed in all formulations. The 75CHT scaffolds supported the most neo-cartilage formation, as demonstrated by an increase in glycosaminoglycan production. In contrast to 100CHT scaffolds, ECM was homogenously deposited on the 75CHT and 50CHT scaffolds. Although mechanical properties of the 50CHT scaffold were better, the 75CHT scaffold facilitated better neo-cartilage formation.

Enhanced differentiation of retinal progenitor cells using microfabricated topographical cues

Due to the retina’s inability to replace photoreceptors lost during retinal degeneration, significant interest has been placed in methods to implant replacement cells. Polymer scaffolds are increasingly being studied as vehicles for cellular delivery to degenerated retinas. Previously, we fabricated poly(methyl methacrylate) thin film scaffolds that increased survival and integration of implanted retinal progenitor cells (RPCs). Additionally, these scaffolds minimized the trauma and cellular response associated with implantation of foreign bodies into mouse eyes. Here, we demonstrate that biodegradable polycaprolactone (PCL) thin film scaffolds can be fabricated with integrated microtopography. Microfabricated topography in a PCL thin film enhanced the attachment and organization of RPCs compared to unstructured surfaces. Using real-time quantitative polymerase chain reaction we also observed that attachment to microtopography induced cellular differentiation. RPCs grown on PCL thin films exhibited an increase in gene expression for the photoreceptor markers recoverin and rhodopsin, an increase in the glial and Müller cell marker GFAP, and a decrease in SOX2 gene expression (a marker for undifferentiated progenitor cells) compared to cells grown on unmodified tissue culture polystyrene (TCPS).

In vivo evaluation of 3-dimensional polycaprolactone scaffolds for cartilage repair in rabbits

BACKGROUND

Cartilage tissue engineering using synthetic scaffolds allows maintaining mechanical integrity and withstanding stress loads in the body, as well as providing a temporary substrate to which transplanted cells can adhere.

PURPOSE

This study evaluates the use of polycaprolactone (PCL) scaffolds for the regeneration of articular cartilage in a rabbit model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Five conditions were tested to attempt cartilage repair. To compare spontaneous healing (from subchondral plate bleeding) and healing due to tissue engineering, the experiment considered the use of osteochondral defects (to allow blood flow into the defect site) alone or filled with bare PCL scaffold and the use of PCL-chondrocytes constructs in chondral defects. For the latter condition, 1 series of PCL scaffolds was seeded in vitro with rabbit chondrocytes for 7 days and the cell/scaffold constructs were transplanted into rabbits' articular defects, avoiding compromising the subchondral bone. Cell pellets and bare scaffolds were implanted as controls in a chondral defect.

RESULTS

After 3 months with PCL scaffolds or cells/PCL constructs, defects were filled with white cartilaginous tissue; integration into the surrounding native cartilage was much better than control (cell pellet). The engineered constructs showed histologically good integration to the subchondral bone and surrounding cartilage with accumulation of extracellular matrix including type II collagen and glycosaminoglycan. The elastic modulus measured in the zone of the defect with the PCL/cells constructs was very similar to that of native cartilage, while that of the pellet-repaired cartilage was much smaller than native cartilage.

CONCLUSION

The results are quite promising with respect to the use of PCL scaffolds as aids for the regeneration of articular cartilage using tissue engineering techniques.