An advanced biphasic porous and injectable scaffold displays a fine balance between mechanical strength and remodeling capabilities essential for cartilage regeneration.

An important challenge in tissue engineering is the regeneration of functional articular cartilage (AC). In the field, biomimetic hydrogels are being extensively studied as scaffolds that recapitulate microenvironmental features or as mechanical supports for transplanted cells. New advanced hydrogel formulations based on salmon methacrylate gelatin (sGelMA), a cold-adapted biomaterial, are presented in this work. The psychrophilic nature of this biomaterial provides rheological advantages allowing the fabrication of scaffolds with high concentrations of the biopolymer and high mechanical strength, suitable for formulating injectable hydrogels with high mechanical strength for cartilage regeneration. However, highly intricate cell-laden scaffolds derived from highly concentrated sGelMA solutions could be deleterious for cells and scaffold remodeling. On this account, the current study proposes the use of sGelMA supplemented with a mesophilic sacrificial porogenic component. The cytocompatibility of different sGelMA-based formulations is tested through the encapsulation of osteoarthritic chondrocytes (OACs) and stimulated to synthesize extracellular matrix (ECM) components in vitro and in vivo. The sGelMA-derived scaffolds reach high levels of stiffness, and the inclusion of porogens impacts positively the scaffold degradability and molecular diffusion, improved fitness of OACs, increased the expression of cartilage-related genes, increased glycosaminoglycan (GAG) synthesis, and improved remodeling toward cartilage-like tissues. Altogether, these data support the use of sGelMA solutions in combination with mammalian solid gelatin beads for highly injectable formulations for cartilage regeneration, strengthening the importance of the balance between mechanical properties and remodeling capabilities.

Etiology of Cartilage Lesions Does Not Affect Clinical Outcomes of Patellofemoral Autologous Chondrocyte Implantation.

OBJECTIVE: To determine the relationship between cartilage lesion etiology and clinical outcomes after second-generation autologous chondrocyte implantation (ACI) in the patellofemoral joint (PFJ) with a minimum of 2 years' follow-up. METHODS: A retrospective review of all patients that underwent ACI in the PFJ by a single surgeon was performed. Seventy-two patients with a mean follow-up of 4.2 ± 2.0 years were enrolled in this study and were stratified into 3 groups based on the etiology of PFJ cartilage lesions: patellar dislocation (group 1; n = 23); nontraumatic lesions, including chondromalacia, osteochondritis dissecans, and degenerative defects (group 2; n = 28); and other posttraumatic lesions besides patellar dislocations (group 3; n = 21). Patient's mean age was 29.6 ± 8.7 years. Patients in group 1 were significantly younger (25.4 ± 7.9 years) than group 2 (31.7 ± 9.6 years; P = 0.025) and group 3 (31.5 ± 6.6 years; P = 0.05). Body mass index averaged 26.2 ± 4.3 kg/m2, with a significant difference between group 1 (24.4 ± 3.2 kg/m2) and group 3 (28.7 ± 4.5 kg/m2; P = 0.005). A clinical comparison was established between groups based on patient-reported outcome measures (PROMs) and failure rates. RESULTS: Neither pre- nor postoperative PROMs differed between groups (P > 0.05). No difference was seen in survivorship between groups (95.7% vs. 82.2% vs. 90.5%, P > 0.05). CONCLUSION: Cartilage lesion etiology did not influence clinical outcome in this retrospective study after second generation ACI in the PFJ. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

BM-MSCs differentiated to chondrocytes for treatment of full-thickness cartilage defect of the knee.

BACKGROUND: Full-thickness articular cartilage injury of the knee is a major cause of disability. The aim of this study is to assess the outcome of patients treated with differentiated to chondrocytes bone marrow mesenchymal stem cells (BM-MSCs) cultured on a collagen type I/III (Chondro-Gide®) scaffold. The secondary aim was to confirm the absence of adverse events. METHODS: Fifteen patients (19 knees) with symptomatic full-thickness cartilage defects of the knee were enrolled. Bone marrow was harvested from the iliac crest, BM-MSCs were prepared, and expanded cells were grown in a standard medium or in a standard culture medium containing TGF-ß. BM-MSCs differentiated to chondrocytes were seeded in a porcine collagen type I/III scaffold (Chondro-Gide®) and cultured in TGF-ß containing media. After 4 weeks, the membrane was sutured on the cartilage defect. All patients underwent plain radiographs (antero-posterior, lateral, and axial view of the patella) and MRI of the affected knee. The Oxford knee score, the Lyhsolm scale, and the VAS score were administered to all patients. At final follow-up a MRI for the study of articular cartilage was undertaken. RESULTS: The mean size of the cartilage lesions was 20 × 17 mm (range, 15 × 10 mm-30 × 30 mm). At final follow-up, the median Oxford knee score and Lyhsolm scale scores significantly improved from 29 (range 12-39; SD 7.39) to 45 (range 24-48; SD 5.6) and from 55.5 (range 25-81; SD 17.7) to 94.5 (58-100; SD 10.8), respectively. Pain, according to the VAS score, significantly improved. Sixty percent of patients reported their satisfaction as excellent, 20% as good, 14% as fair, and 1 patient as poor. CONCLUSION: The treatment of full-thickness chondral injuries of the knee with differentiated to chondrocytes BM-MSCs and Chondro-Gide® scaffold showed encouraging outcomes. Further studies involving more patients, and with longer follow-up, are required to evaluate the effectiveness of the treatment and the long-term results.

Atelocolageno combinado con microperforaciones para el tratamiento de lesiones condrales severas en la rodilla / Atelocollagen matrix combined with microfractures in severe knee articular cartilage injuries

Introducción: En la actualidad existen diferentes métodos y técnicas de preservación articular. La utilización de una matriz de atelocolágeno combinada con microperforaciones otorga un soporte adecuado para la inducción de la condrogénesis a partir de las células mesenquimales provenientes de la médula ósea. El objetivo de nuestro trabajo es describir la técnica quirúrgica y presentar los resultados de una serie de pacientes con lesiones condrales severas, tratados con microperforaciones asociado a una matriz de atelocolágeno. Material y Método: Se evaluaron los pacientes intervenidos quirúrgicamente por lesión de cartílago grado IV de más de 3 cm2 a los que se le aplicó matriz de atelocolágeno combinado con microperforaciones. El mínimo seguimiento fue de 24 meses. En pacientes con deseje o inestabilidad asociada se realizaron procedimientos combinados en el mismo acto quirúrgico. Describimos la técnica quirúrgica, resultados funcionales pre y postoperatorios con las escalas de Lysholm, IKDC y Escala Visual Análoga (EVA) del dolor fueron. Se realizó una evaluación radiográfica. Analizamos las complicaciones del procedimiento. Resultado: Fueron operados 12 pacientes. A uno se le realizó un reemplazo articular de su rodilla a los 10 meses de la cirugía y fue considerado falla con finalización del seguimiento. Once fueron evaluados clínicamente, nueve hombres y dos mujeres, con una edad promedio de 48 años y seguimiento promedio de 34 meses. Ocho procedimientos en cóndilo interno, 2 en cóndilo externo y 4 en tróclea. La mediana de la escala de IKDC pre/post operatorio fue 41/55 (p 0.016), Lysholm 35/82 (p 0.004) y EVA 9/3 (p 0.002). La evaluación radiológica no evidenció cambios degenerativos. Se registró 1 artrofibrosis post operatoria. Conclusión: En nuestra serie, el tratamiento con atelocolágeno combinado con microperforaciones mejoró la clínica de los pacientes con lesión severa del cartílago articular de rodilla. Tipo de trabajo: Serie de casos Nivel de Evidencia: IV

ntroduction: Different surgical approaches are currently available to treat knee chondral defects. The technique used in this article combines microfractures with the use of an injectable atelocollagen matrix (Cartifill). The matrix covers the defect and improves the mechanical stability of the blood clot and maintains the chondrogenic progenitor cells and growth factors in the defective area. The aim of our study is to evaluate and describe the results in a series of patients treated with atelocollagen matrix and microfractures. Material and Methods: All patients treated with atelocollagen matrix due to a cartilage lesion with a minimum follow-up of 24 months were evaluated. Patients undergoing associated surgeries (osteotomies, meniscectomies, mosaicplasty, ligament reconstruction) in the same surgical procedure were included in the study. Clinical function was assessed before and after surgery with the International Knee Documentation Committee (IKDC), the Lysholm score and the Visual Analogue Scale (VAS). Radiographic control was requested according to availability. Results: Twelve patients met the inclusion criteria. Three women. Average age of 50 years. Eight applications in medial condyle, 2 in lateral condyle and 4 in trochlea. One post-operative arthrofibrosis was recorded. One of the patients underwent an articular replacement of his knee 10 months after the surgery with finalization of follow-up. The pre / post-operative average was 39/52 (IKDC), 37/76 (Lysholm) and 8.5 / 3.5 (VAS). Conclusion: In our series, atelocollagen matrix combined with microfractures improved the clinical symptoms of patients with severe knee articular cartilage injury. However, a better selection of patients who require this procedure should be applied in future interventions. Type of Study: Case Series. Level of Evidence: IV

Implantación de condrocitos autólogos versus microfracturas para el tratamiento de lesiones del cartílago en la rodilla / Autologous chondrocytes implantation versus microfracture for the treatment of knee cartilage lesions

Resumen: Objetivo: Comparar la eficacia clínica y la seguridad de la terapia de microfracturas (MF) versus implantación de condrocitos autólogos en membrana (MACI) en el manejo de lesiones condrales de rodilla ≥ 3 cm2 y el seguimiento a 12 meses postratamiento. Material y métodos: Se realizó un estudio de cohorte retrospectiva, de Enero de 2016 a Diciembre de 2017. Se incluyeron pacientes con una o varias lesiones condrales en rodilla ≥ 3 cm2 para comparar la terapia MF versus MACI para la reparación de lesión condral. Se realizaron valoraciones clínicas y funcionales previas al tratamiento quirúrgico y 12 meses posteriores, con medición de los arcos de movimiento, escala EVA, Oxford e índice de Lequesne. Resultados: Se incluyeron 12 pacientes en MF y 12 pacientes en MACI. La lesión más frecuente se localizó en la patela en ocho pacientes (67%). Se demostró incremento en los arcos de movimiento, así como mejoría en la comparación entre el nivel basal y en el seguimiento a 12 meses: en EVA, MF mostró 48.4% y MACI 57.5% (p ≤ 0.05); escala de Oxford: MF 32.65% y MACI 51.04% (p ≤ 0.05); índice de Lequesne: MF 40.12% y MACI 50%. Se presentaron dos casos de derrame articular en MACI, que se resolvieron con la realización de artrotomías. Conclusión: En este estudio se demostró mejoría significativa en MACI con alivio del dolor, funcionalidad y arcos de movimiento en comparación con el tratamiento de MF en lesiones ≥ 3 cm2 del cartílago articular de rodilla después de un año de seguimiento.

Abstract: Objective: To compare the clinical efficacy and safety of microfracture therapy (MF) versus implantation of autologous chondrocytes (MACI) in the management of chondral lesions of the knee ≥ 3 cm2 and follow up to 12 months post treatment. Material and methods: A retrospective cohort study was conducted from January 2016 to December 2017. Patients with one or more chondral lesions in knee ≥ 3 cm2 were included to compare MF versus MACI therapy for the repair of chondral lesion. Clinical and functional evaluations were carried out prior to the surgical treatment and 12 months later, with measurement of the range of motion, EVA, Oxford scale and Lequesne index. Results: Twelve patients were included in MF and 12 patients in MACI. The most frequent lesion was located in the Patella in eight patients (67%). It showed an increase in the arcs of motion, as well as improvement in the comparison between baseline and follow-up at 12 months: in EVA, MF demonstrated 48.4% and MACI 57.5% (p ≤ 0.05); Oxford scale: MF 32.65% and MACI 51.04% (p ≤ 0.05); index of Lequesne: MF 40.12% and MACI 50%. Two cases of joint effusion were presented in MACI, which were resolved with the realization of arthrotomies. Conclusion: In this study, significant improvement was demonstrated in MACI with pain relief, functionality, and range of motion compared to the treatment of MF in lesions ≥ 3 cm2 of the articular cartilage of the knee after one year of follow-up.

Reoperation Rates After Cartilage Restoration Procedures in the Knee: Analysis of a Large US Commercial Database.

The purpose of this study is to describe the rate of return to the operating room (OR) following microfracture (MFX), autologous chondrocyte implantation (ACI), osteochondral autograft transplantation (OATS), and osteochondral allograft (OCA) procedures at 90 days, 1 year, and 2 years. Current Procedural Terminology codes for all patients undergoing MFX, ACI, OATS, and OCA were used to search a prospectively collected, commercially available private payer insurance company database from 2007 to 2011. Within 90 days, 1 year, and 2 years after surgery, the database was searched for the occurrence of these same patients undergoing knee diagnostic arthroscopy with biopsy, lysis of adhesions, synovectomy, arthroscopy for infection or lavage, arthroscopy for removal of loose bodies, chondroplasty, MFX, ACI, OATS, OCA, and/or knee arthroplasty. Descriptive statistical analysis and contingency table analysis were performed. A total of 47,207 cartilage procedures were performed from 2007 to 2011, including 43,576 MFX, 640 ACI, 386 open OATS, 997 arthroscopic OATS, 714 open OCA, and 894 arthroscopic OCA procedures. The weighted average reoperation rates for all procedures were 5.87% at 90 days, 11.94% at 1 year, and 14.90% at 2 years following the index cartilage surgery. At 2 years, patients who underwent MFX, ACI, OATS, OCA had reoperation rates of 14.65%, 29.69%, 8.82%, and 12.22%, respectively. There was a statistically significantly increased risk for ACI return to OR within all intervals (P < .0001); however, MFX had a greater risk factor (P < .0001) for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative treatment options. With a large US commercial insurance database from 2007 to 2011, reparative procedures were favored for chondral injuries, but yielded an increased risk for conversion to arthroplasty. There was no difference in failure/revision rates between the restorative approaches, yet cell-based approaches yielded a significantly increased risk for a return to the OR.

Temporomandibular joint regeneration: proposal of a novel treatment for condylar resorption after orthognathic surgery using transplantation of autologous nasal septum chondrocytes, and the first human case report.

BACKGROUND: Upon orthognathic mandibular advancement surgery the adjacent soft tissues can displace the distal bone segment and increase the load on the temporomandibular joint causing loss of its integrity. Remodeling of the condyle and temporal fossa with destruction of condylar cartilage and subchondral bone leads to postsurgical condylar resorption, with arthralgia and functional limitations. Patients with severe lesions are refractory to conservative treatments, leading to more invasive therapies that range from simple arthrocentesis to open surgery and prosthesis. Although aggressive and with a high risk for the patient, surgical invasive treatments are not always efficient in managing the degenerative lesions. METHODS: We propose a regenerative medicine approach using in-vitro expanded autologous cells from nasal septum applied to the first proof-of-concept patient. After the required quality controls, the cells were injected into each joint by arthrocentesis. Results were monitored by functional assays and image analysis using computed tomography. RESULTS: The cell injection fully reverted the condylar resorption, leading to functional and structural regeneration after 6 months. Computed tomography images showed new cortical bone formation filling the former cavity space, and a partial recovery of condylar and temporal bones. The superposition of the condyle models showed the regeneration of the bone defect, reconstructing the condyle original form. CONCLUSIONS: We propose a new treatment of condylar resorption subsequent to orthognathic surgery, presently treated only by alloplastic total joint replacement. We propose an intra-articular injection of autologous in-vitro expanded cells from the nasal septum. The proof-of-concept treatment of a selected patient that had no alternative therapeutic proposal has given promising results, reaching full regeneration of both the condylar cartilage and bone at 6 months after the therapy, which was fully maintained after 1 year. This first case is being followed by inclusion of new patients with a similar pathological profile to complete an ongoing stage I/II study. TRIAL REGISTRATION: This clinical trial is approved by the National Commission of Ethics in Medical Research (CONEP), Brazil, CAAE 12484813.0.0000.5245, and retrospectively registered in the Brazilian National Clinical Trials Registry and in the USA Clinical Trials Registry under the Universal Trial Number (UTN) U1111-1194-6997 .

[Autologous chondrocytes implantation versus microfracture for the treatment of knee cartilage lesions]. / Implantación de condrocitos autólogos versus microfracturas para el tratamiento de lesiones del cartílago en la rodilla.

OBJECTIVE: To compare the clinical efficacy and safety of microfracture therapy (MF) versus implantation of autologous chondrocytes (MACI) in the management of chondral lesions of the knee 3 cm2 and follow up to 12 months post treatment. MATERIAL AND METHODS: A retrospective cohort study was conducted from January 2016 to December 2017. Patients with one or more chondral lesions in knee 3 cm2 were included to compare MF versus MACI therapy for the repair of chondral lesion. Clinical and functional evaluations were carried out prior to the surgical treatment and 12 months later, with measurement of the range of motion, EVA, Oxford scale and Lequesne index. RESULTS: Twelve patients were included in MF and 12 patients in MACI. The most frequent lesion was located in the Patella in eight patients (67%). It showed an increase in the arcs of motion, as well as improvement in the comparison between baseline and follow-up at 12 months: in EVA, MF demonstrated 48.4% and MACI 57.5% (p 0.05); Oxford scale: MF 32.65% and MACI 51.04% (p 0.05); index of Lequesne: MF 40.12% and MACI 50%. Two cases of joint effusion were presented in MACI, which were resolved with the realization of arthrotomies. CONCLUSION: In this study, significant improvement was demonstrated in MACI with pain relief, functionality, and range of motion compared to the treatment of MF in lesions 3 cm2 of the articular cartilage of the knee after one year of follow-up.

OBJETIVO: Comparar la eficacia clínica y la seguridad de la terapia de microfracturas (MF) versus implantación de condrocitos autólogos en membrana (MACI) en el manejo de lesiones condrales de rodilla 3 cm2 y el seguimiento a 12 meses postratamiento. MATERIAL Y MÉTODOS: Se realizó un estudio de cohorte retrospectiva, de Enero de 2016 a Diciembre de 2017. Se incluyeron pacientes con una o varias lesiones condrales en rodilla 3 cm2 para comparar la terapia MF versus MACI para la reparación de lesión condral. Se realizaron valoraciones clínicas y funcionales previas al tratamiento quirúrgico y 12 meses posteriores, con medición de los arcos de movimiento, escala EVA, Oxford e índice de Lequesne. RESULTADOS: Se incluyeron 12 pacientes en MF y 12 pacientes en MACI. La lesión más frecuente se localizó en la patela en ocho pacientes (67%). Se demostró incremento en los arcos de movimiento, así como mejoría en la comparación entre el nivel basal y en el seguimiento a 12 meses: en EVA, MF mostró 48.4% y MACI 57.5% (p 0.05); escala de Oxford: MF 32.65% y MACI 51.04% (p 0.05); índice de Lequesne: MF 40.12% y MACI 50%. Se presentaron dos casos de derrame articular en MACI, que se resolvieron con la realización de artrotomías. CONCLUSIÓN: En este estudio se demostró mejoría significativa en MACI con alivio del dolor, funcionalidad y arcos de movimiento en comparación con el tratamiento de MF en lesiones 3 cm2 del cartílago articular de rodilla después de un año de seguimiento.

Co-culture of dedifferentiated and primary human chondrocytes obtained from cadaveric donor enhance the histological quality of repair tissue: an in-vivo animal study.

To compare the quality of the repair tissue in three-dimensional co-culture of human chondrocytes implanted in an in vivo model. Six cadaveric and five live human donors were included. Osteochondral biopsies from the donor knees were harvested for chondrocyte isolation. Fifty percent of cadaveric chondrocytes were expanded until passage-2 (P2) while the remaining cells were cryopreserved in passage-0 (P0). Fresh primary chondrocytes (P0f) obtained from live human donors were co-cultured. Three-dimensional constructs were prepared with a monolayer of passage-2 chondrocytes, collagen membrane (Geistlich Bio-Gide®), and pellet of non-co-cultured (P2) or co-cultured chondrocytes (P2 + P0c, P2 + P0f). Constructs were implanted in the subcutaneous tissue of athymic mice and left for 3 months growth. Safranin-O and Alcian blue staining were used to glycosaminoglycan content assessment. Aggrecan and type-II collagen were evaluated by immunohistochemistry. New-formed tissue quality was evaluated with an adaptation of the modified O'Driscoll score. Histological quality of non-co-cultured group was 4.37 (SD ±4.71), while co-cultured groups had a mean score of 8.71 (SD ±3.98) for the fresh primary chondrocytes and 9.57 (SD ±1.27) in the cryopreserved chondrocytes. In immunohistochemistry, Co-culture groups were strongly stained for type-II and aggrecan not seen in the non-co-cultured group. It is possible to isolate viable chondrocytes from cadaveric human donors in samples processed in the first 48-h of dead. There is non-significant difference between the numbers of chondrocytes isolated from live or cadaveric donors. Cryopreservation of cadaveric primary chondrocytes does not alter the capability to form cartilage like tissue. Co-culture of primary and passaged chondrocytes enhances the histological quality of new-formed tissue compared to non-co-cultured cells.

* Thermosensitive Poly(N-vinylcaprolactam) Injectable Hydrogels for Cartilage Tissue Engineering.

Injectable hydrogels have gained prominence in the field of tissue engineering for minimally invasive delivery of cells for tissue repair and in the filling of irregular defects. However, many injectable hydrogels exhibit long gelation times or are not stable for long periods after injection. To address these concerns, we used thermosensitive poly(N-vinylcaprolactam) (PNVCL) hydrogels due to their cytocompatibility and fast response to temperature stimuli. Changes in the PNVCL molecular weight and concentration enabled the development of hydrogels with tunable mechanical properties and fast gelation times (<60 s when the temperature was raised from room temperature to physiologic temperature). Chondrocytes (CHs) and mesenchymal stem cells were encapsulated in PNVCL hydrogels and exhibited high viability (∼90%), as monitored by Live/Dead staining and Alamar Blue assays. Three-dimensional constructs of CH-laden PNVCL hydrogels supported cartilage-specific extracellular matrix production both in vitro and after subcutaneous injection in nude rats for up to 8 weeks. Moreover, biochemical analyses of constructs demonstrated a time-dependent increase in glycosaminoglycans (GAGs) and collagen, which were significantly augmented in the implants cultured in vivo. Histological analyses also demonstrated regular distribution of synthesized cartilage components, including abundant GAGs and type II collagen. The findings from this study demonstrate thermosensitive PNVCL as a candidate injectable biomaterial to deliver cells for cartilage tissue engineering.

Construction of a tissue engineered intervertebral disc with high biological activity using an allogeneic intervertebral disc supplemented with transfected nucleus pulposus cells expressing exogenous dopamine beta-hydroxylase.

This study addressed the in vitro construction and biological activity of tissue engineered intervertebral discs with exogenous human dopamine beta-hydroxylase (DBH) nucleus pulposus cells. pSNAV2.0-DBH expression plasmids were utilized to enhance the survival rates of intervertebral disc tissue cells. Various concentrations of transfected nucleus pulposus cells were injected into the discs, and DBH mRNA expression was determined using polymerase chain reaction amplification. Polysaccharide content and total collagen protein content in the engineered disc nucleus pulposus tissue were determined. The visible fluorescence intensities of the 1 x 10(5) and 1 x 10(6) groups vs the 1 x 10(4) group were significantly increased (P < 0.05); no significant difference was observed between the 1 x 10(5) and 1 x 10(6) groups (P > 0.05) at 7 days after injection. DBH mRNA expression could be detected in the all but the EGFP control group at 14 days culture. No significant difference was observed in the protein content between the 1 x 10(4) and the control groups at various times, while the protein content was significantly higher in the 1 x 10(5) vs the control and the 1 x 10(4) groups at 7-, 14-, and 21-day cultures. These results demonstrate that a tissue engineered intervertebral disc with high biological activity can be constructed by utilizing allogeneic intervertebral discs stored in liquid nitrogen and a 1 x 10(5) transfected nucleus pulposus cell complex with in vitro culture for 14 days. This model can be used in animal experiments to study the biological activity of the engineered discs.

Platelet rich plasma associated with heterologous fresh and thawed chondrocytes on osteochondral lesions of rabbits / Associação de plasma rico em plaquetas e condrócitos heterólogos frescos e descongelados em lesão osteocondral de coelhos

Chondrocytes obtained from stifle joint of New Zealand White rabbits were cultivated. Half of cells were maintained in culture for later implantation and the others frozen during six months to evaluate viability. A circular osteochondral defect was created in the right stifle of other twenty seven rabbits. The control group (CG) received no treatment. The thawed (TH) and fresh (FH) heterologous groups received, respectively, an implant of cultivated thawed or fresh heterologous chondrocytes associated with platelet rich plasma (PRP). The CG group showed greatest pain and lameness compared to the other groups seven days after the implantation. Microscopically, at 45 and 90 days, the TH and FH groups showed filling with cartilaginous tissue containing chondrocytes surrounded by a dense matrix of glycosaminoglycans. In the CG group, healing occurred with vascularized fibrous connective tissue without integration to the subchondral bone. Cryopreserved heterologous chondrocytes were viable for implantation and healing of osteochondral lesions; the association with PRP allows the fixation of cells in the lesion and offers growth factors which accelerates repair with tissue similar to articular hyaline cartilage.

Cultivaram-se condrócitos obtidos da articulação do joelho de coelhos. Metade das células foi mantida em cultura para posterior implantação, e a outra metade foi congelada durante seis meses com a finalidade de avaliar a viabilidade. Criou-se um defeito circular osteocondral no joelho direito de outros vinte e sete coelhos. O grupo controle (GC) não recebeu tratamento. Os grupos descongelado (TH) e fresco (FH) receberam, respectivamente, implantes heterólogos de condrócitos cultivados descongelados e frescos, associados com PRP. O grupo GC apresentou maior dor e claudicação em comparação com os outros grupos aos sete dias após o implante. Microscopicamente, aos 45 e 90 dias, os grupos TH e FH mostraram preenchimento da falha com tecido cartilaginoso contendo condrócitos circundados por uma matriz densa de glicosaminoglicanos. Nesse período, no grupo CG, a cura ocorreu com tecido conjuntivo fibroso vascularizado e sem integração com o osso subcondral. Condrócitos heterólogos criopreservados foram viáveis para implantação e tratamento de lesões osteocondrais; a associação com o PRP permitiu a fixação de células na lesão e ofereceu fatores de crescimento que aceleraram a reparação com o tecido semelhante à cartilagem hialina articular.

Platelet rich plasma associated with heterologous fresh and thawed chondrocytes on osteochondral lesions of rabbits / Associação de plasma rico em plaquetas e condrócitos heterólogos frescos e descongelados em lesão osteocondral de coelhos

Chondrocytes obtained from stifle joint of New Zealand White rabbits were cultivated. Half of cells were maintained in culture for later implantation and the others frozen during six months to evaluate viability. A circular osteochondral defect was created in the right stifle of other twenty seven rabbits. The control group (CG) received no treatment. The thawed (TH) and fresh (FH) heterologous groups received, respectively, an implant of cultivated thawed or fresh heterologous chondrocytes associated with platelet rich plasma (PRP). The CG group showed greatest pain and lameness compared to the other groups seven days after the implantation. Microscopically, at 45 and 90 days, the TH and FH groups showed filling with cartilaginous tissue containing chondrocytes surrounded by a dense matrix of glycosaminoglycans. In the CG group, healing occurred with vascularized fibrous connective tissue without integration to the subchondral bone. Cryopreserved heterologous chondrocytes were viable for implantation and healing of osteochondral lesions; the association with PRP allows the fixation of cells in the lesion and offers growth factors which accelerates repair with tissue similar to articular hyaline cartilage.(AU)

Cultivaram-se condrócitos obtidos da articulação do joelho de coelhos. Metade das células foi mantida em cultura para posterior implantação, e a outra metade foi congelada durante seis meses com a finalidade de avaliar a viabilidade. Criou-se um defeito circular osteocondral no joelho direito de outros vinte e sete coelhos. O grupo controle (GC) não recebeu tratamento. Os grupos descongelado (TH) e fresco (FH) receberam, respectivamente, implantes heterólogos de condrócitos cultivados descongelados e frescos, associados com PRP. O grupo GC apresentou maior dor e claudicação em comparação com os outros grupos aos sete dias após o implante. Microscopicamente, aos 45 e 90 dias, os grupos TH e FH mostraram preenchimento da falha com tecido cartilaginoso contendo condrócitos circundados por uma matriz densa de glicosaminoglicanos. Nesse período, no grupo CG, a cura ocorreu com tecido conjuntivo fibroso vascularizado e sem integração com o osso subcondral. Condrócitos heterólogos criopreservados foram viáveis para implantação e tratamento de lesões osteocondrais; a associação com o PRP permitiu a fixação de células na lesão e ofereceu fatores de crescimento que aceleraram a reparação com o tecido semelhante à cartilagem hialina articular.(AU)

Clinical and experimental approaches to knee cartilage lesion repair and mesenchymal stem cell chondrocyte differentiation.

Cartilage has poor regeneration capacity due to the scarcity of endogenous stem cells, its low metabolic activity and the avascular environment. Repair strategies vary widely, including microfracture, autologous or allogenic tissue implantation, and in vitro engineered tissues of autologous origin. However, unlike the advances that have been made over more than two decades with more complex organs, including vascular, cardiac or bone tissues, similar advances in tissue engineering for cartilage repair are lacking. Although the inherent characteristics of cartilage tissue, such as the lack of vascularity and low cellular diversity, suggest that it would be one of the more simple tissues to be engineered, its functional weight-bearing role and implant viability and adaptation make this type of repair more complex. Over the last decade several therapeutic approaches and innovative techniques show promise for lasting and functional regeneration of hyaline cartilage. Here we will analyze the main strategies for cartilage regeneration and discuss our experience.

Clinical and experimental approaches to knee cartilage lesion repair and mesenchymal stem cell chondrocyte differentiation

Cartilage has poor regeneration capacity due to the scarcity of endogenous stem cells, its low metabolic activity and the avascular environment. Repair strategies vary widely, including microfracture, autologous or allogenic tissue implantation, and in vitro engineered tissues of autologous origin. However, unlike the advances that have been made over more than two decades with more complex organs, including vascular, cardiac or bone tissues, similar advances in tissue engineering for cartilage repair are lacking. Although the inherent characteristics of cartilage tissue, such as the lack of vascularity and low cellular diversity, suggest that it would be one of the more simple tissues to be engineered, its functional weight-bearing role and implant viability and adaptation make this type of repair more complex. Over the last decade several therapeutic approaches and innovative techniques show promise for lasting and functional regeneration of hyaline cartilage. Here we will analyze the main strategies for cartilage regeneration and discuss our experience.

Transplante autólogo de condrócitos / Autologous chondrocyte implantation

Esta revisão da literatura descreve o processo do transplante autólogo de condrócitos em todas as suas etapas, indicações clínicas, técnica operatória, técnica laboratorial, reabilitação e resultados clínicos. Desde 1994, quando a técnica de ACI foi descrita pela primeira vez, este procedimento foi aprimorado e tornou-se uma das mais importantes alternativas cirúrgicas para o tratamento das lesões condrais do joelho. Nivel de Evidência II, Prospectivo Comparativo.

This literature review article describes the autologous chondrocyte implantation (ACI) process - its stages, clinical indications, surgical technique, laboratory protocol, rehabilitation and clinical outcomes. Since 1994, when the ACI was described for the first time, the procedure has improved to become one of the most important surgical alternatives for the treatment of chondral lesions of the knee.

Neurotrophic regulation of fibroblast dedifferentiation during limb skeletal regeneration in the axolotl (Ambystoma mexicanum).

The ability of animals to repair tissue damage is widespread and impressive. Among tissues, the repair and remodeling of bone occurs during growth and in response to injury; however, loss of bone above a threshold amount is not regenerated, resulting in a "critical-size defect" (CSD). The development of therapies to replace or regenerate a CSD is a major focus of research in regenerative medicine and tissue engineering. Adult urodeles (salamanders) are unique in their ability to regenerate complex tissues perfectly, yet like mammals do not regenerate a CSD. We report on an experimental model for the regeneration of a CSD in the axolotl (the Excisional Regeneration Model) that allows for the identification of signals to induce fibroblast dedifferentiation and skeletal regeneration. This regenerative response is mediated in part by BMP signaling, as is the case in mammals; however, a complete regenerative response requires the induction of a population of undifferentiated, regeneration-competent cells. These cells can be induced by signaling from limb amputation to generate blastema cells that can be grafted to the wound, as well as by signaling from a nerve and a wound epithelium to induce blastema cells from fibroblasts within the wound environment.

Transplante autólogo de condrócitos: relato de três casos / Autologous chondrocyte implantation: series of 3 cases

A cartilagem hialina recobre as superfícies articulares e tem um papel importante na redução da fricção e da carga mecânica das articulações sinoviais, como o joelho. Este tecido não é suprido de vasos, nervos ou circulação linfática, o que pode ser uma das razões pela qual a cartilagem articular tem uma péssima capacidade de cicatrização. As lesões condrais, quando atingem o osso subcondral (lesão osteocondral), não cicatrizam e podem progredir para artrose com o passar do tempo. Em pacientes jovens, o tratamento dos defeitos condrais do joelho ainda é um desafio, principalmente as lesões maiores de 4cm. Uma das opções de tratamento nesses pacientes é o transplante autólogo de condrócitos, que por não violar o osso subcondral e por reparar o defeito com tecido semelhante à cartilagem hialina, teria a vantagem teórica de ser mais biológico e mecanicamente superior, quando comparado a outras técnicas. Descreveremos nesse artigo a experiência do Instituto de Ortopedia e Traumatologia do Hospital das Clínicas da Universidade de São Paulo (IOT-HCFMUSP) com o transplante autólogo de condrócitos (ACI), através do relato de três casos.

Hyaline cartilage in the surface of synovial joints plays an important role in lowering stress and attrition in joints such as the knee. This tissue has no blood vessels, nerves, nor lymphatic drainage, which in part explains why articular cartilage has such poor capacity for healing. Chondral lesions reaching the subchondral bone (osteochondral lesions) do not heal and may progress to osteoarthritis as time passes. In young patients, treatment of such defects is challenging, especially in lesions larger than 4 cm. One option in young adults is the autologous chondrocyte implantation, capable of filling the defect with tissue similar to hyaline cartilage without violating the subchondral bone. Theoretically, it has biological and mechanical advantages over other surgical options. In this paper, we describe the experience with this procedure in a series of 3 cases at the Institute of Orthopedics and Traumatology, University of São Paulo.

Knee chondral lesions treated with autologous chondrocyte transplantation in a tridimensional matrix: clinical evaluation at 1-year follow-up.

BACKGROUND: Despite the many studies on chondral injury repair, no outcomes have been evaluated with the Western Ontario and McMaster (WOMAC) Universities osteoarthritis index, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Oxford Knee Score, all of which are specific for evaluating the presence of osteoarthritis. MATERIALS AND METHODS: We evaluated the clinical progress of patients following autologous chondrocyte implantation (ACI) performed by our Bone and Tissue Bank using a technique in which cells, instead of being introduced to the articular defect in a liquid form, are implanted into a tridimensional matrix of semisolid collagen (Condrograft((R))). A total of 22 patients underwent the procedure, 15 of whom were available for a 1-year follow-up that included clinical evaluation by WOMAC score before and after surgery and KOOS and the Oxford Knee Score after surgery. RESULTS: The results were improved WOMAC score from 56.4 before surgery to 16.2 after surgery (P < 0.002), average KOOS score of 83.6, and average Oxford Knee Score of 18.8. CONCLUSIONS: These results indicate that our tridimensional matrix technique effectively improved patients' quality of life, at least in the short term, and delayed any subsequent procedure. Long-term assessment is necessary to determine the true value of this technique.