A study on the effect of degradation media on the physical and mechanical properties of porous PLGA 85/15 scaffolds

Computational Analysis of Biodegradable Polyester Materials for Biomedical Applications: Investigating Molecular Weight Change due to Hydrolysis

Biopolymers have gained significant importance in the field of biomedicine, particularly in addressing organ and tissue loss in living organisms. These polymers exhibit temporary functionality during treatment and undergo biodegradation once their intended purpose is fulfilled. The diverse characteristics of these biopolymers expand their range of applications, albeit necessitating extensive experimentation and a time commitment for thorough investigation. Computational models have emerged as a promising avenue for predictive analysis, complementing traditional experimental methods. In this study, we delve into the degradation dynamics of polyester materials with a specific emphasis on the hydrolysis process. We employed an appropriate reaction diffusion model to unveil the underlying mechanisms governing material weight loss and erosion within a two-dimensional framework for a rectangular slice of the implant. By bridging computational modeling with empirical research, this study provides valuable insights into the behavior of biopolymers, contributing to a deeper understanding of these materials and their potential for advanced biomedical applications. To illustrate this framework's effectiveness, we conducted a case study using experimental data from the literature, focusing on poly(d,l-lactic acid) material.

Silane-modified hydroxyapatite nanoparticles incorporated into polydioxanone/poly(lactide-co-caprolactone) creates a novel toughened nanocomposite with improved material properties and in vivo inflammatory responses

The interface tissue between bone and soft tissues, such as tendon and ligament (TL), is highly prone to injury. Although different biomaterials have been developed for TL regeneration, few address the challenges of the TL-bone interface. Here, we aim to develop novel hybrid nanocomposites based on poly(p-dioxanone) (PDO), poly(lactide-co-caprolactone) (LCL), and hydroxyapatite (HA) nanoparticles suitable for TL-bone interface repair. Nanocomposites, containing 3-10% of both unmodified and chemically modified hydroxyapatite (mHA) with a silane coupling agent. We then explored biocompatibility through in vitro and in vivo studies using a subcutaneous mouse model. Through different characterisation tests, we found that mHA increases tensile properties, creates rougher surfaces, and reduces crystallinity and hydrophilicity. Morphological observations indicate that mHA nanoparticles are attracted by PDO rather than LCL phase, resulting in a higher degradation rate for mHA group. We found that adding the 5% of nanoparticles gives a balance between the properties. In vitro experiments show that osteoblasts' activities are more affected by increasing the nanoparticle content compared with fibroblasts. Animal studies indicate that both HA and mHA nanoparticles (10%) can reduce the expression of pro-inflammatory cytokines after six weeks of implantation. In summary, this work highlights the potential of PDO/LCL/HA nanocomposites as an excellent biomaterial for TL-bone interface tissue engineering applications.

Current Trend and New Opportunities for Multifunctional Bio-Scaffold Fabrication via High-Pressure Foaming

Biocompatible and biodegradable foams prepared using the high-pressure foaming technique have been widely investigated in recent decades as porous scaffolds for in vitro and in vivo tissue growth. In fact, the foaming process can operate at low temperatures to load bioactive molecules and cells within the pores of the scaffold, while the density and pore architecture, and, hence, properties of the scaffold, can be finely modulated by the proper selection of materials and processing conditions. Most importantly, the high-pressure foaming of polymers is an ideal choice to limit and/or avoid the use of cytotoxic and tissue-toxic compounds during scaffold preparation. The aim of this review is to provide the reader with the state of the art and current trend in the high-pressure foaming of biomedical polymers and composites towards the design and fabrication of multifunctional scaffolds for tissue engineering. This manuscript describes the application of the gas foaming process for bio-scaffold design and fabrication and highlights some of the most interesting results on: (1) the engineering of porous scaffolds featuring biomimetic porosity to guide cell behavior and to mimic the hierarchical architecture of complex tissues, such as bone; (2) the bioactivation of the scaffolds through the incorporation of inorganic fillers and drugs.

In Vitro Degradation of 3D-Printed Poly(L-lactide-Co-Glycolic Acid) Scaffolds for Tissue Engineering Applications

The creation of scaffolds for cartilage tissue engineering has faced significant challenges in developing constructs that can provide sufficient biomechanical support and offer suitable degradation characteristics. Ideally, such tissue-engineering techniques necessitate the fabrication of scaffolds that mirror the mechanical characteristics of the articular cartilage while degrading safely without damaging the regenerating tissues. The aim of this study was to create porous, biomechanically comparable 3D-printed scaffolds made from Poly(L-lactide-co-glycolide) 85:15 and to assess their degradation at physiological conditions 37 °C in pH 7.4 phosphate-buffered saline (PBS) for up to 56 days. Furthermore, the effect of scaffold degradation on the cell viability and proliferation of human bone marrow mesenchymal stem cells (HBMSC) was evaluated in vitro. To assess the long-term degradation of the scaffolds, accelerated degradation tests were performed at an elevated temperature of 47 °C for 28 days. The results show that the fabricated scaffolds were porous with an interconnected architecture and had comparable biomechanical properties to native cartilage. The degradative changes indicated stable degradation at physiological conditions with no significant effect on the properties of the scaffold and biocompatibility of the scaffold to HBMSC. Furthermore, the accelerated degradation tests showed consistent degradation of the scaffolds even in the long term without the notable release of acidic byproducts. It is hoped that the fabrication and degradation characteristics of this scaffold will, in the future, translate into a potential medical device for cartilage tissue regeneration.

Construction of tissue-customized hydrogels from cross-linkable materials for effective tissue regeneration

Hydrogels are prevalent scaffolds for tissue regeneration because of their hierarchical architectures along with outstanding biocompatibility and unique rheological and mechanical properties. For decades, researchers have found that many materials (natural, synthetic, or hybrid) can form hydrogels using different cross-linking strategies. Traditional strategies for fabricating hydrogels include physical, chemical, and enzymatical cross-linking methods. However, due to the diverse characteristics of different tissues/organs to be regenerated, tissue-customized hydrogels need to be developed through precisely controlled processes, making the manufacture of hydrogels reliant on novel cross-linking strategies. Thus, hybrid cross-linkable materials are proposed to tackle this challenge through hybrid cross-linking strategies. Here, different cross-linkable materials and their associated cross-linking strategies are summarized. From the perspective of the major characteristics of the target tissues/organs, we critically analyze how different cross-linking strategies are tailored to fit the regeneration of such tissues and organs. To further advance this field, more appropriate cross-linkable materials and cross-linking strategies should be investigated. In addition, some innovative technologies, such as 3D bioprinting, the internet of medical things (IoMT), and artificial intelligence (AI), are also proposed to improve the development of hydrogels for more efficient tissue regeneration.

Hard Dental Tissues Regeneration-Approaches and Challenges

With the development of the modern concept of tissue engineering approach and the discovery of the potential of stem cells in dentistry, the regeneration of hard dental tissues has become a reality and a priority of modern dentistry. The present review reports the recent advances on stem-cell based regeneration strategies for hard dental tissues and analyze the feasibility of stem cells and of growth factors in scaffolds-based or scaffold-free approaches in inducing the regeneration of either the whole tooth or only of its component structures.

In Vitro Degradation of Electrospun Poly(Lactic-Co-Glycolic Acid) (PLGA) for Oral Mucosa Regeneration

Poly(lactic-co-glycolic acid) (PLGA) has been used in the field of tissue engineering as a scaffold due to its good biocompatibility, biodegradability and mechanical strength. With the aim to explore the degradability of PLGA electrospun nonwoven structures for oral mucosa tissue engineering applications, non-irradiated and gamma irradiated nonwovens were immersed in three different solutions, in which simulated body fluid (SBF) and artificial saliva are important for future oral mucosa tissue engineering. The nonwovens were immersed for 7, 15 and 30 days in SBF, culture media (DMEM) and artificial saliva at 37 °C. Before immersion in the solutions, the dosage of 15 kGy was applied for sterilization in one assay and compared with non-irradiated samples at the same timepoints. Samples were characterized using different techniques such as scanning electron microscopy (SEM), differential scanning calorimetric (DSC) and gel permeation chromatography (GPC) to evaluate the nonwoven degradation and Fourier-transform infrared spectroscopy (FTIR) to evaluate the chain scissions. Our results showed that PLGA nonwovens were constituted by semicrystalline fibers with moderate degradation properties up to thirty days. The non-irradiated samples exhibited slower kinetics of degradation than irradiated nonwovens. For immersion times longer than 7 days in the three different solutions, the mean diameter of irradiated fibers stayed in the same range, but significantly different from the control sample. On non-irradiated samples, the degradation kinetics was slower and the plateau in the diameter value was only attained after 30 days of immersion in the fluids. Plasticization (fluid absorption into the fiber structure) occurred in the bulk material, as confirmed by a decrease in Tg observed by DSC analyses of non-irradiated and irradiated nonwovens, in comparison with the respective controls. In addition, artificial saliva showed a higher capacity of influencing PLGA crystallization than SBF and DMEM. FTIR analyses showed typical PLGA chemical functional groups changes. These results will be important for future application of those PLGA electrospun nonwovens for oral mucosa regeneration.

Poly(lactic-co-glycolic acid)(PLGA)/TiO2 nanotube bioactive composite as a novel scaffold for bone tissue engineering: In vitro and in vivo studies

The aim of this study was to synthesize and characterize novel three-dimensional porous scaffolds made of poly (lactic-co-glycolic acid)/TiO₂ nanotube (TNT) composite microspheres for bone tissue engineering applications. The incorporation of TNT greatly increases mechanical properties of PLGA/TNT microsphere-sintered scaffold. The experimental results exhibit that the PLGA/0.5 wt% TNT scaffold sintered at 100 °C for 3 h showed the best mechanical properties and a proper pore structure for tissue engineering. Biodegradation test ascertained that the weight of both PLGA and PLGA/PLGA/0.5 wt% TiO₂ nanotube composites slightly reduced during the first 4 weeks following immersion in SBF solution. Moreover, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and alkaline phosphatase activity (ALP activity) results represent increased cell viability for PLGA/0.5%TNT composite scaffold in comparison to the control group. In vivo studies show the amount of bone formation for PLGA/TNT was approximately twice of pure PLGA. Vivid histologic images of the newly generated bone on the implants further supported our test results. Eventually, a mathematical model showed that both PLGA and PLGA/TNT scaffolds' mechanical properties follow an exponential trend with time as their degradation occurs. By a three-dimensional finite element model, a more monotonous distribution of stress was present in the scaffold due to the presence of TNT with a reduction in maximum stress on bone.

In vitro degradation behavior of a hydroxyapatite/poly(lactide-co-glycolide) composite reinforced by micro/nano-hybrid poly(glycolide) fibers for bone repair

A poly(glycolide) (PGA) fiber-reinforced hydroxyapatite/poly(lactide-co-glycolide) (HA/PLGA) composite with high mechanical strength has been prepared previously.

Tailoring the delivery of therapeutic ions from bioactive scaffolds while inhibiting their apatite nucleation: a coaxial electrospinning strategy for soft tissue regeneration

Control the release of ions as a function of the shell thickness. Inhibit hydroxyapatite nucleation. Improve mechanical properties.

In situ nanomechanical characterization of the early stages of swelling and degradation of a biodegradable polymer

The interactions of a biodegradable scaffold with cells or living tissues depend on the time-evolution of the nanoscale properties of the scaffold. We present an in situ quantitative study on the early-stage swelling and degradation of poly(lactic-co-glycolic acid) (PLGA). A novel metrology scheme based on force microscopy measurements of the patterns of PLGA nanostructures is developed to characterize the evolution of topography, volume and nanomechanical properties. The volume and nanoscale roughness show an oscillating behaviour during the first eight days of immersion; at a later stage, we observe a continuous decrease of the volume. The effective Young's modulus exhibits a monotonic decrease from an initial value of about 2.4 GPa down to 9 MPa at day 14. The oscillating behaviour of the volume before the onset of full degradation is explained by a coupled diffusion-swelling mechanism. The appearance of a second maximum in the volume evolution results from the competition between swelling and degradation.

Creep loading during degradation attenuates mechanical property loss in PLGA

While absorbable materials and medical devices primarily degrade through hydrolysis, their degradation kinetics are sensitive to environmental conditions, including temperature, pH, and mechanical loading. While there is some consistent information in the literature suggesting that strain controlled loading accelerates strength loss, there is much more limited information on the interaction between degradation and mechanical load applied under force control. Force control conditions impose a different stress state on the material and therefore, may exhibit different effects on degradation. In this study, the interaction between loading and degradation rate for an exemplary absorbable polymer, poly(l-lactide-co-glycolide), was investigated. The results indicated that load during degradation results in significant polymer creep, which is associated with increased force loss, but decreased strength loss (i.e., stress based parameters such as ultimate stress). This study further identified that changes to the degradation kinetics from exposure to loading were not associated with alterations to polymer crystallinity but were associated with delayed loss of molecular weight. Overall, these results demonstrate the importance of investigating the interaction between loading and degradation and that physical changes, such as those induced by creep, rather than chemical changes offer the strongest explanation for alteration of degradation kinetics.

Relating pore size variation of poly (ɛ-caprolactone) scaffolds to molecular weight of porogen and evaluation of scaffold properties after degradation

The major challenge in designing a scaffold for fabricating tissue engineered blood vessels is optimization of its microstructure for supporting uniform cellular in-growth with good mechanical integrity and degradation kinetics suitable for long-term implantation. In this study, we have investigated the feasibility of varying the pore size of poly(ɛ-caprolactone) (PCL) scaffold by altering the molecular weight of porogen and studied the effect of degradation on morphological characteristics and mechanical properties of scaffolds by correlating to the extent of degradation. Scaffolds with two different pore sizes were prepared by solvent casting and particulate leaching where poly(ethylene glycol) (PEG) porogens having two molecular weights (3400 and 8000) were used and subjected to in vitro degradation in phosphate buffered saline (PBS) upto six months. Microcomputed tomography studies of scaffolds revealed narrower pore size distribution when PEG-3400 was used as porogen and had 78% pores in the 12-24 µ range, whereas incorporation of PEG-8000 resulted in broader distribution with only 65% pores in the same range. Degradation resulted in scaffolds with narrower pore size distribution to have better retention of morphological and mechanical characteristics compared to scaffolds with broader distribution. Gravimetric and molecular weight studies also showed that scaffold degradation in both cases was only in initial stages after 6 months and PCL scaffolds had potential to be recommended for vascular tissue engineering applications.

Effect of biodegradation and de novo matrix synthesis on the mechanical properties of valvular interstitial cell-seeded polyglycerol sebacate-polycaprolactone scaffolds

The development of living heart valves that grow with the patient is a promising strategy for heart valve replacements in pediatric patients. Despite active research in the field of tissue engineered heart valves there have been limited efforts to optimize the balance between biodegradation of the scaffolds and de novo extracellular matrix (ECM) synthesis by cells and study their consequences on the mechanical properties of the cell-seeded construct. This study investigates the effect of in vitro degradation and ECM secretion on the mechanical properties of hybrid polyester scaffolds. The scaffolds were synthesized from blends of fast degrading polyglycerol sebacate (PGS) and slowly degrading polycaprolactone (PCL). PGS-PCL scaffolds were electrospun using a 2:1 ratio of PGS to PCL. Accelerated hydrolytic degradation in 0.1 mM sodium hydroxide revealed 2-fold faster degradation of PGS-PCL scaffolds compared with PCL scaffolds. Thermal analysis and scanning electron microscopy demonstrated marginal change in PCL scaffold properties, while PGS-PCL scaffolds showed preferential mass loss of PGS and thinning of the individual fibers during degradation. Consequently, the mechanical properties of PGS-PCL scaffolds decreased gradually with no significant change for PCL scaffolds during accelerated degradation. Valvular interstitial cells (VICs) seeded on PGS-PCL scaffolds showed higher ECM protein secretion compared with PCL. Thus the mechanical properties of the cell-seeded PCL scaffolds did not change significantly compared with acellular scaffolds, probably due to slower degradation and ECM deposition by VICs. In contrast, the PGS-PCL scaffolds exhibited a gradual decrease in the mechanical properties of the acellular scaffolds due to degradation, which was compensated for by new matrix secreted by VICs seeded on the scaffolds. Our study demonstrated that the faster degrading PGS component of PGS-PCL accelerated the degradation rate of the scaffolds. VICs, on the other hand, were able to remodel the synthetic scaffold, depositing new matrix proteins and maintaining the mechanical properties of the scaffolds.

Improved chondrogenesis and engineered cartilage formation from TGF-β3-expressing adipose-derived stem cells cultured in the rotating-shaft bioreactor

Adipose-derived stem cells (ASCs) have captured growing interests for cartilage regeneration. Although ASCs chondrogenesis can be stimulated by genetic modification, whether genetically engineered ASCs hold promise for the cartilaginous tissue formation remains to be explored. Since baculovirus (an emerging gene delivery vector) effectively transduced ASCs and transforming growth factor β3 (TGF-β3) was recently shown to induce ASCs chondrogenesis more potently than TGF-β1, we constructed a baculoviral vector (Bac-CT3W) to encode TGF-β3. The Bac-CT3W-transduced ASCs expressed TGF-β3 robustly and substantiated the chondrogenesis of ASCs cultured in monolayer and in porous scaffolds. Culture of the transduced cell/scaffold constructs in the rotating-shaft bioreactor (RSB) under hypoxic and perfusion conditions for 2 weeks further augmented the ASCs chondrogenesis and deposition of cartilage-specific collagen II and glycosaminoglycans, leading to the formation of cartilage-like tissues with hyaline appearance and compressive modulus approaching 62% of the native articular cartilage. Intriguingly, prolonged culture to 3 or 4 weeks failed to further augment the construct growth, probably due to the scaffold degradation. Altogether, baculovirus-mediated TGF-β3 expression in ASCs in conjunction with dynamic culture in the RSB for 2 weeks synergistically ameliorated the ASCs chondrogenesis and formation of cartilaginous tissues, representing a novel approach to producing engineered cartilages.

Biomaterial scaffolds in cartilage–subchondral bone defects influencing the repair of autologous articular cartilage transplants

The repair of articular cartilage typically involves the repair of cartilage–subchondral bone tissue defects. Although various bioactive materials have been used to repair bone defects, how these bioactive materials in subchondral bone defects influence the repair of autologous cartilage transplant remains unclear. The aim of this study was to investigate the effects of different subchondral biomaterial scaffolds on the repair of autologous cartilage transplant in a sheep model. Cylindrical cartilage–subchondral bone defects were created in the right femoral knee joint of each sheep. The subchondral bone defects were implanted with hydroxyapatite–β-tricalcium phosphate (HA–TCP), poly lactic-glycolic acid (PLGA)-HA–TCP dual-layered composite scaffolds (PLGA/HA–TCP scaffolds), or autologous bone chips. The autologous cartilage layer was placed on top of the subchondral materials. After 3 months, the effect of different subchondral scaffolds on the repair of autologous cartilage transplant was systematically studied by investigating the mechanical strength, structural integration, and histological responses. The results showed that the transplanted cartilage layer supported by HA–TCP scaffolds had better structural integration and higher mechanical strength than that supported by PLGA/HA–TCP scaffolds. Furthermore, HA–TCP-supported cartilage showed higher expression of acid mucosubstances and glycol-amino-glycan contents than that supported by PLGA/HA–TCP scaffolds. Our results suggested that the physicochemical properties, including the inherent mechanical strength and material chemistry of the scaffolds, play important roles in influencing the repair of autologous cartilage transplants. The study may provide useful information for the design and selection of proper subchondral biomaterials to support the repair of both subchondral bone and cartilage defects.

Biomedical Applications of Biodegradable Polymers

Utilization of polymers as biomaterials has greatly impacted the advancement of modern medicine. Specifically, polymeric biomaterials that are biodegradable provide the significant advantage of being able to be broken down and removed after they have served their function. Applications are wide ranging with degradable polymers being used clinically as surgical sutures and implants. In order to fit functional demand, materials with desired physical, chemical, biological, biomechanical and degradation properties must be selected. Fortunately, a wide range of natural and synthetic degradable polymers has been investigated for biomedical applications with novel materials constantly being developed to meet new challenges. This review summarizes the most recent advances in the field over the past 4 years, specifically highlighting new and interesting discoveries in tissue engineering and drug delivery applications.

Tuning the microstructure and biodegradation of three-phase scaffolds for bone regeneration made of PCL, Zein, and HA

The aim of this study has been the design of novel multi-phase porous scaffolds with bi-modal pore size distributions and controlled biodegradation rate for bone tissue engineering (bTE), via a gas foaming—leaching approach. Poly( ε-caprolactone) (PCL) has been melt mixed with thermoplastic zein (TZ) and hydroxyapatite particle, to prepare multi-phase PCL—TZ and PCL—TZ—HA composites suitable to be further processed for the fabrication of 3D porous scaffolds. To this aim, these systems have been gas foamed by using CO2 as blowing agent and, subsequently, soaked in H2O to leach out the plasticizer from the TZ. This combined process allows the formation of an interpenetrated micro- and macro-porosity network within the samples. The effect of the different formulations on the micro-structural properties and in vitro biodegradation of the scaffolds has been investigated, and the results correlated to the mechanisms involved in the formation of the bi-modal pore structure. Results demonstrated that the multi-phase nature of the biomaterials prepared as well as their composition significantly affect the micro-structural properties and biodegradation rate of the scaffolds. The optimal selection of the processing conditions may allow for the design of multi-phase 3D porous scaffolds suitable for bTE.

Developing biodegradable scaffolds for tissue engineering of the urethra

OBJECTIVE

To develop a synthetic biodegradable alternative to using human allodermis for the production of tissue-engineered buccal mucosa for substitution urethroplasty, looking specifically at issues of sterilization and cell-seeding protocols and, comparing the results to native buccal mucosa.

MATERIAL AND METHODS

Three methods of sterilization, peracetic acid (PAA), γ-irradiation and ethanol, were evaluated for their effects on a biodegradable electrospun scaffold of polylactide-co-glycolide (PLGA, 85:15), to identify a sterilization method with minimal adverse effects on the scaffolds. Two protocols for seeding oral cells on the scaffold were compared, co-culture of fibroblasts and keratinocytes on the scaffolds for 14 days, and seeding fibroblasts for 5 days then adding keratinocytes for a further 10 days. Cell viability and proliferation on the scaffolds, scaffold contraction and mechanical properties of the scaffolds with and without cells were examined.

RESULTS

γ-irradiation and PAA sterilized scaffolds remained sterile for >3 months when incubated in antibiotic-free culture medium, while ethanol sterilized and unsterilized samples became infected within 2-14 days. All scaffolds showed extensive contraction (up to 50% over 14 days) irrespective of the method of sterilization or the presence of cells. All methods of sterilization, particularly ethanol, reduced the tensile strength of the scaffolds. The addition of cells tended to further reduce mechanical properties but increased elasticity. The cell-seeding protocol of adding fibroblasts for 5 days followed by keratinocytes for 10 days was the most promising, achieving a mean (sem) ultimate tensile stress of 1.20 (0.24) × 10⁵ N/m² compared to 3.77 (1.05) × 10⁵ N/m² for native buccal mucosa, and a Young's modulus of 2.40 (0.25) MPa, compared to 0.73 (0.09) MPa for the native buccal mucosa.

CONCLUSION

This study adds to our understanding of how sterilization and cell seeding affect the physical properties of scaffolds. Both PAA and γ-irradiation appear to be suitable methods for sterilizing PLGA scaffolds, although both reduce the tensile properties of the scaffolds. Cells grow well on the sterilized scaffolds, and with our current protocol produce constructs which have ≈ 30% of the mechanical strength and elasticity of the native buccal mucosa. We conclude that sterilized PLGA 85:15 is a promising material for producing tissue-engineered buccal mucosa.

The evaluation of a biphasic osteochondral implant coupled with an electrospun membrane in a large animal model

Conventional clinical therapies are unable to resolve osteochondral defects adequately; hence, tissue engineering solutions are sought to address the challenge. A biphasic implant that was seeded with mesenchymal stem cells (MSCs) and coupled with an electrospun membrane was evaluated as an alternative. This dual phase construct comprised of a polycaprolactone (PCL) cartilage scaffold and a PCL-tricalcium phosphate osseous matrix. Autologous MSCs were seeded into the entire implant via fibrin and the construct was inserted into critically sized osteochondral defects located at the medial condyle and patellar groove of pigs. The defect was resurfaced with a PCL-collagen electrospun mesh, which served as a substitute for periosteal flap in preventing cell leakage. Controls without either implanted MSCs or resurfacing membrane were included. After 6 months, cartilaginous repair was observed with a low occurrence of fibrocartilage at the medial condyle. Osteochondral repair was promoted and host cartilage degeneration was arrested as shown by superior glycosaminoglycan maintenance. This positive morphological outcome was supported by a higher relative Young's modulus, which indicated functional cartilage restoration. Bone ingrowth and remodeling occurred in all groups, with a higher degree of mineralization in the experimental group. Tissue repair was compromised in the absence of the implanted cells or the resurfacing membrane. Moreover, healing was inferior at the patellar groove when compared with the medial condyle and this was attributed to the native biomechanical features.