Jia-Kuo Yu

A New Source of Mesenchymal Stem Cells for Articular Cartilage Repair MSCs Derived From Mobilized Peripheral Blood Share Similar Biological Characteristics In Vitro and Chondrogenesis In Vivo as MSCs From Bone Marrow in a Rabbit Model

Background: Bone marrow (BM) has been considered as a major source of mesenchymal stem cells (MSCs), but it has many disadvantages in clinical application. However, MSCs from peripheral blood (PB) could be obtained by a less invasive method and be more beneficial for autologous transplantation than BM MSCs, which makes PB a promising source for articular cartilage repair in clinical use. Purpose: To assess whether MSCs from mobilized PB of New Zealand White rabbits have similar biological characteristics in vitro and chondrogenesis in vivo as BM MSCs. Study Design: Controlled laboratory study. Methods: A combined method of drug administration containing granulocyte colony stimulating factor (G-CSF) plus CXCR4 antagonist AMD3100 was adopted to mobilize the PB stem cells of adult New Zealand White rabbits in vitro. The isolated cells were identified as MSCs by morphological characteristics, surface markers, and differentiation potentials. A comparison between PB MSCs and BM MSCs was made in terms of biological characteristics in vitro and chondrogenesis in vivo. This issue was investigated from the aspects of morphology, immune phenotype, multiple differentiation capacity, expansion potential, antiapoptotic capacity, and ability to repair cartilage defects in vivo of PB MSCs compared with BM MSCs. Results: Peripheral blood MSCs were successfully mobilized by the method of combined drug administration, then isolated, expanded, and identified in vitro. No significant difference was found concerning the morphology, immune phenotype, and antiapoptotic capacity between PB MSCs and BM MSCs. Significantly, MSCs from both sources compounded with decalcified bone matrix showed the same ability to repair cartilage defects in vivo. For multipluripotency, BM MSCs exhibited a more osteogenic potential and higher proliferation capacity than PB MSCs, whereas PB MSCs possessed a stronger adipogenic and chondrogenic differentiation potential than BM MSCs in vitro. Conclusion: Although there are some differences in the proliferation and differentiation aspects between the 2 sources, PB MSCs share certain similar biological characteristics in vitro and chondrogenesis in vivo as BM MSCs. Clinical Relevance: These results suggest that PB MSCs are a new source of seed cells used in articular cartilage repair.

Diagnostic Values of 3 Methods for Evaluating Meniscal Healing Status After Meniscal Repair: Comparison Among Second-Look Arthroscopy, Clinical Assessment, and Magnetic Resonance Imaging

Background: The main diagnostic methods for evaluating repaired menisci include second-look arthroscopy, clinical assessment, and magnetic resonance imaging (MRI). None of the previous studies applied all 3 methods for each consecutive case nor made any systematic comparison among them. Purpose: This study was undertaken to compare the diagnostic values of the 3 different methods in an attempt to propose suggestions for evaluating meniscal healing results. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Eighty-one patients (89 menisci), with a mean age of 25.4 years (standard deviation [SD], 7.7; range, 15-50 years), underwent arthroscopic meniscal repair, including 65 medial menisci and 24 lateral menisci. Follow-up evaluation for each meniscus included clinical assessment, second-look arthroscopy, and postoperative MRI, with a mean follow-up time of 25.4 months (SD, 6.0; range, 17.4-48.3 months). Defined criteria for unhealed meniscus were any symptoms such as joint-line tenderness, swelling, locking, or positive McMurray test for clinical assessment; cleft or instability on second-look arthroscopy; and grade 3 signal intensity shown at the repaired site on postoperative MRI. Results: Seventy-seven menisci were confirmed completely healed by second-look arthroscopy, with a total healing rate of 86.5%. Clinical assessment found 63 menisci healed, with a clinical healing rate of 70.8% (sensitivity, 58.3%; specificity, 75.3%; accuracy, 73.0%). By using the second-look arthroscopy as the standard, the sensitivity, specificity, and accuracy, respectively, were calculated for MRI in 5 sequences: sagittal T1: 91.7%, 58.4%, 62.9%; sagittal proton density (PD): 83.3%, 40.3%, 46.1%; sagittal T2: 58.3%, 89.6%, 85.4%; coronal PD: 75.0%, 74.0%, 74.2%; and coronal T2: 41.7%, 98.7%, 91.0%. Conclusion: Second-look arthroscopy was the most dependable way to determine meniscal healing. Clinical assessment had obvious limitations in diagnosing healed menisci. On MRI examination, T2-weighted sequences had obviously higher specificity and accuracy, while PD and T1 had higher sensitivity. The diagnostic value could be improved by a combined application of different sequences.

Kartogenin-Incorporated Thermogel Supports Stem Cells for Significant Cartilage Regeneration

Recently, cartilage tissue engineering (CTE) attracts increasing attention in cartilage defect repair. In this work, kartogenin (KGN), an emerging chondroinductive nonprotein small molecule, was incorporated into a thermogel of poly(L-lactide-co-glycolide)-poly(ethylene glycol)-poly(L-lactide-co-glycolide) (PLGA-PEG-PLGA) to fabricate an appropriate microenvironment of bone marrow mesenchymal stem cells (BMSCs) for effective cartilage regeneration. More integrative and smoother repaired articular surface, more abundant characteristic glycosaminoglycans (GAGs) and collagen II (COL II), and less degeneration of normal cartilage were obtained in the KGN and BMSCs coloaded thermogel group in vivo. In conclusion, the KGN-loaded PLGA-PEG-PLGA thermogel can be utilized as an alternative support for BMSCs to regenerate damaged cartilage in vivo.

Role of scaffold mean pore size in meniscus regeneration

UNLABELLED Recently, meniscus tissue engineering offers a promising management for meniscus regeneration. Although rarely reported, the microarchitectures of scaffolds can deeply influence the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation in meniscus tissue engineering. Herein, a series of three-dimensional (3D) poly(ε-caprolactone) (PCL) scaffolds with three distinct mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The scaffold with the mean pore size of 215μm significantly improved both the proliferation and extracellular matrix (ECM) production/deposition of mesenchymal stem cells compared to all other groups in vitro. Moreover, scaffolds with mean pore size of 215μm exhibited the greatest tensile and compressive moduli in all the acellular and cellular studies. In addition, the relatively better results of fibrocartilaginous tissue formation and chondroprotection were observed in the 215μm scaffold group after substituting the rabbit medial meniscectomy for 12weeks. Overall, the mean pore size of 3D-printed PCL scaffold could affect cell behavior, ECM production, biomechanics, and repair effect significantly. The PCL scaffold with mean pore size of 215μm presented superior results both in vitro and in vivo, which could be an alternative for meniscus tissue engineering. STATEMENT OF SIGNIFICANCE Meniscus tissue engineering provides a promising strategy for meniscus regeneration. In this regard, the microarchitectures (e.g., mean pore size) of scaffolds remarkably impact the behaviors of cells and subsequent tissue formation, which has been rarely reported. Herein, three three-dimensional poly(ε-caprolactone) scaffolds with different mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The results suggested that the mean pore size significantly affected the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation. This study furthers our understanding of the cell-scaffold interaction in meniscus tissue engineering, which provides unique insight into the design of meniscus scaffolds for future clinical application.

Comparative study on immediate versus delayed meniscus allograft transplantation: 4- to 6-year follow-up.

Background: Meniscus allograft transplantation (MAT) is generally used for patients who sustain symptoms after meniscectomy, which could be called delayed MAT. Meniscus allograft transplantation for patients immediately after meniscectomy has not been reported. Hypothesis: Compared with the conventional delayed MAT, immediate MAT might provide better clinical results and reduce joint degeneration. Study Design: Cohort study; Level of evidence, 3. Methods: The study was performed with 18 transplanted menisci (6 medial, 12 lateral) from 16 patients. Eight menisci were transplanted immediately after meniscectomy (IM group); 10 menisci, from patients who complained of knee symptoms at a mean time of 35 months (range, 9-92 months) after total meniscectomy, underwent delayed transplantation (DE group). Fourteen patients undergoing meniscectomy during the same period were included as controls (ME group). Degenerative changes in knee joints were evaluated by plain radiographs and magnetic resonance imaging (MRI). Allograft extrusion and relative percentage of extrusion were measured on MRI. Other outcome assessments included preoperative and postoperative International Knee Documentation Committee (IKDC), Tegner, and Lysholm scores; visual analog scale (VAS) for pain; and range of motion and isokinetic muscle strength evaluation. Results: The mean length of follow-up was 50.8 months (range, 44-62 months) for the IM group, 72.0 months (range, 44-94 months) for the DE group, and 54.3 months (range, 45-62 months) for the ME group. A statistically significant difference in favor of the IM and ME groups was found on the VAS (0.4 [IM group] vs 1.1 [ME group] vs 2.5 [DE group]) and muscle strength (P < .05). The mean IKDC score in the IM group was significantly higher than that in the DE group (93 [range, 85-99] vs 74 [range, 38-95], respectively; P < .05). The IM group showed significantly less preoperative to postoperative cartilage degeneration changes on radiographs and MRI when compared with the DE and ME groups (Kellgren-Lawrence score changes: 0.25 [IM group] vs 1.0 [DE group] vs 1.7 [ME group]; Yulish score changes: 0.25 [IM group] vs 1.0 [DE group] vs 1.1 [ME group]; P < .05). Extrusion of the allograft was observed in the body of the menisci in all patients. No significant difference was found in terms of the Lysholm score, Tegner score, joint narrowing, or meniscus extrusion (P > .05). Conclusion: Compared with delayed MAT, immediate MAT led to more satisfactory subjective results, less joint degeneration, and less muscle strength deficits. The short-term results of delayed meniscus transplantation were close to those of meniscectomy.

3D-Printed Poly(ε-caprolactone) Scaffold Augmented With Mesenchymal Stem Cells for Total Meniscal Substitution: A 12- and 24-Week Animal Study in a Rabbit Model

Background: Total meniscectomy leads to knee osteoarthritis in the long term. The poly(ε-caprolactone) (PCL) scaffold is a promising material for meniscal tissue regeneration, but cell-free scaffolds result in relatively poor tissue regeneration and lead to joint degeneration. Hypothesis: A novel, 3-dimensional (3D)–printed PCL scaffold augmented with mesenchymal stem cells (MSCs) would offer benefits in meniscal regeneration and cartilage protection. Study Design: Controlled laboratory study. Methods: PCL meniscal scaffolds were 3D printed and seeded with bone marrow–derived MSCs. Seventy-two New Zealand White rabbits were included and were divided into 4 groups: cell-seeded scaffold, cell-free scaffold, sham operation, and total meniscectomy alone. The regeneration of the implanted tissue and the degeneration of articular cartilage were assessed by gross and microscopic (histological and scanning electron microscope) analysis at 12 and 24 weeks postoperatively. The mechanical properties of implants were also evaluated (tensile and compressive testing). Results: Compared with the cell-free group, the cell-seeded scaffold showed notably better gross appearance, with a shiny white color and a smooth surface. Fibrochondrocytes with extracellular collagen type I, II, and III and proteoglycans were found in both seeded and cell-free scaffold implants at 12 and 24 weeks, while the results were significantly better for the cell-seeded group at week 24. Furthermore, the cell-seeded group presented notably lower cartilage degeneration in both femur and tibia compared with the cell-free or meniscectomy group. Both the tensile and compressive properties of the implants in the cell-seeded group were significantly increased compared with those of the cell-free group. Conclusion: Seeding MSCs in the PCL scaffold increased its fibrocartilaginous tissue regeneration and mechanical strength, providing a functional replacement to protect articular cartilage from damage after total meniscectomy. Clinical Relevance: The study suggests the potential of the novel 3D PCL scaffold augmented with MSCs as an alternative meniscal substitution, although this approach requires further improvement before being used in clinical practice.

Meniscus transplantation using treated xenogeneic meniscal tissue: viability and chondroprotection study in rabbits.

PURPOSE This was a preliminary study performed in vivo to evaluate the viability and the chondroprotective effects of irradiated deep-frozen xenogeneic meniscal tissue as a novel substitute for meniscus transplantation. METHODS Medial meniscectomies were performed on the right knees of 48 New Zealand white rabbits. The inner one-third of pig meniscus was harvested and then irradiated and deeply frozen. The treated xenogeneic meniscal tissues were then transplanted to 24 right knees (Xeno group), whereas 24 other knees received meniscus allograft transplantations (Allo group). The left knees of the Xeno group and Allo group received meniscectomies (Meni group) and sham operations (Sham group), respectively. The rabbits were killed at weeks 6, 12, and 24 postoperatively. The newly formed structure of the implanted tissue and cartilage of the medial compartment of each group was assessed by gross and semiquantitative histologic analysis. RESULTS After 24 weeks, the implanted xenogeneic meniscal tissue completely healed to the synovium and formed meniscus-like tissue. The chondrocyte-like cell infiltrated into the tissue with extracellular matrix including type II collagen and proteoglycans. The Xeno group showed significantly less cartilage degeneration than that of the Meni group in the medial tibial plateau at week 24 (P < .05). No significant difference was found between the Xeno group and the Allo group except for the meniscus-covered regions at week 24. From week 12 to week 24, almost no advanced cartilage degeneration was found in weight-bearing regions of the medial tibial plateau of the Xeno group. CONCLUSIONS The treated xenogeneic meniscal tissue healed to the synovium with tissue regeneration and slowed down articular cartilage degeneration in the short-term. The chondroprotection of xenograft transplantation was similar to that of allograft transplantation. CLINICAL RELEVANCE The treated xenogeneic meniscal tissue showed the potential for viability and slowed cartilage degeneration, but more studies are required for application in humans in the future.

Repair of large full-thickness cartilage defect by activating endogenous peripheral blood stem cells and autologous periosteum flap transplantation combined with patellofemoral realignment.

Minimal-invasive procedure and one-step surgery offer autologous mesenchymal stem cells derived from peripheral blood (PB-MSCs) a promising prospective in the field of cartilage regeneration. We report a case of a 19-year-old male athlete of kickboxing with ICRS grade IV chondral lesions at the 60° region of lateral femoral trochlea, which was repaired by activating endogenous PB-MSCs plus autologous periosteum flap transplantation combined with correcting the patellofemoral malalignment. After a 7.5 year follow-up, the result showed that the patient returned to competitive kickboxing. Second-look under arthroscopy showed a smooth surface at 8 months postoperation. The IKDC 2000 subjective score, Lysholm score and Tegner score were 95, 98 and 9 respectively at the final follow up. CT and MRI evaluations showed a significant improvement compared with those of pre-operation.

Effect of repeated freezing–thawing on the Achilles tendon of rabbits

The increased use of allograft tissue in the reconstruction of anterior cruciate ligament has brought more focus to the effect of storage and treatment on allograft. The purpose of this study was to observe the effect of histology and biomechanics on Achilles tendon in rabbits through repeated freezing–thawing before allograft tendon transplantation. Rabbit Achilles tendons were harvested and processed according to the manufacture’s protocol of tissue bank, and freezing–thawing was repeated three times (group 1) and ten times (group 2). Those received only one cycle were used as controls. Then, tendons in each group were selected randomly to make for histological observations and biomechanics test. Histological observation showed that the following changes happened as the number of freezing–thawing increased: the arrangement of tendon bundles and collagen fibrils became disordered until ruptured, cells disrupted and apparent gaps appeared between tendon bundle because the formation of ice crystals. There were significant differences between the experimental and control groups in the values of maximum load, energy of maximum load and maximum stress, whereas no significant differences existed in other values such as stiffness, maximum strain, elastic modulus, and energy density. Therefore, repeated freezing–thawing had histological and biomechanical effect on Achilles tendon in rabbits before allograft tendon transplantation. This indicates that cautions should be taken in the repeated freezing–thawing preparation of allograft tendons in clinical application.

Second-Look Arthroscopic Evaluation of Chondral Lesions After Isolated Anterior Cruciate Ligament Reconstruction Single- Versus Double-Bundle Reconstruction

Background: Double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) has been reported to yield better joint stability than single-bundle (SB) reconstruction. Few studies have compared the 2 techniques with regard to postoperative articular cartilage changes. Hypothesis: Less cartilage damage should occur in the short term after DB ACLR than after SB ACLR. Study Design: Cohort study; Level of evidence, 2. Methods: The study included 52 patients (27 in the DB group and 25 in the SB group) with no chondral or meniscus injury at primary ACLR, as confirmed under arthroscopy. Four-strand and 6- to 8-strand hamstring autografts, respectively, were used for transtibial SB and 4-tunnel DB reconstruction. Each graft was fixed with an EndoButton bioabsorbable interference screw and a staple. Cartilage status at 6 identified regions was evaluated by second-look arthroscopy and the Outerbridge classification. Other assessments at final follow-up included International Knee Documentation Committee (IKDC) score, Tegner and Lysholm scores, side-to-side difference on KT-2000 arthrometer, and range of motion. Results: The mean time from reconstruction to second-look arthroscopy was 18.2 and 17.3 months for the DB and SB groups, respectively. Both groups had cartilage lesions at the patellofemoral joint (patella, 9 vs 13; trochlea, 5 vs 12) and the medial compartment (1 vs 2). Significantly less severe lesions were found in the DB group than in the SB group (mean grade, 0.33 vs 0.96; P < .05). No significant differences were found between the 2 groups in terms of cartilage status at other regions, IKDC score, Lysholm score, Tegner score, KT-2000 arthrometer anterior laxity, or range of motion. Conclusion: Chondral lesions were found postoperatively in both DB and SB ACLR groups with hamstring autograft. The DB ALCR led to less cartilage damage at the femoral trochlea at short-term follow-up.