Tomoyuki Mochizuki

Humeral Insertion of the Supraspinatus and Infraspinatus. New Anatomical Findings Regarding the Footprint of the Rotator Cuff

BACKGROUND It is generally believed that the supraspinatus is the most commonly involved tendon in rotator cuff tears. Clinically, however, atrophy of the infraspinatus muscle is frequently observed in patients with even small to medium-size rotator cuff tears. This fact cannot be fully explained by our current understanding of the anatomical insertions of the supraspinatus and infraspinatus. The purpose of this study was to reinvestigate the humeral insertions of these tendons. METHODS The study included 113 shoulders from sixty-four cadavers. The humeral insertion areas of the supraspinatus and infraspinatus were investigated in ninety-seven specimens. In sixteen specimens, all muscular portions of the supraspinatus and infraspinatus were removed, leaving the tendinous portions intact, in order to define the specific characteristics of the tendinous portion of the muscles. Another twenty-six shoulders were used to obtain precise measurements of the footprints of the supraspinatus and infraspinatus. RESULTS The supraspinatus had a long tendinous portion in the anterior half of the muscle, which always inserted into the anteriormost area of the highest impression on the greater tuberosity and which inserted into the superiormost area of the lesser tuberosity in 21% of the specimens. The footprint of the supraspinatus was triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm. The infraspinatus had a long tendinous portion in the superior half of the muscle, which curved anteriorly and extended to the anterolateral area of the highest impression of the greater tuberosity. The footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. CONCLUSIONS The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus.

Comparison of mesenchymal tissues-derived stem cells for in vivo chondrogenesis: suitable conditions for cell therapy of cartilage defects in rabbit

We previously compared mesenchymal stem cells (MSCs) from a variety of mesenchymal tissues and demonstrated that synovium-MSCs had the best expansion and chondrogenic ability in vitro in humans and rats. In this study, we compared the in vivo chondrogenic potential of rabbit MSCs. We also examined other parameters to clarify suitable conditions for in vitro and in vivo cartilage formation. MSCs were isolated from bone marrow, synovium, adipose tissue, and muscle of adult rabbits. Proliferation potential and in vitro chondrogenic potential were compared. Toxicity of the tracer DiI for in vitro chondrogenesis was also examined. MSCs from each tissue were embedded in collagen gel and transplanted into full thickness cartilage defects of rabbits. Cartilage matrix production was compared histologically. The effects of cell density and periosteal patch on the in vivo chondrogenic potential of synovium-MSCs were also examined. Synovium- and muscle-MSCs had a higher proliferation potential than other cells. Pellets from synovium- and bone-marrow-MSCs showed abundant cartilage matrix. DiI had no significant influence on in vitro cartilage formation. After transplantation into cartilage defects, synovium- and bone-marrow-MSCs produced much more cartilage matrix than other cells. When synovium-MSCs were transplanted at a higher cell density and with a periosteal patch, more abundant cartilage matrix was observed. Thus, synovium- and bone-marrow-MSCs had greater in vivo chondrogenic potential than adipose- and muscle-MSCs, but synovium-MSCs had the advantage of a greater proliferation potential. Higher cell density and a periosteum patch were needed to obtain a high production of cartilage matrix by synovium-MSCs.

Humeral Insertion of the Supraspinatus and Infraspinatus

BACKGROUND It is generally believed that the supraspinatus is the most commonly involved tendon in rotator cuff tears. Clinically, however, atrophy of the infraspinatus muscle is frequently observed in patients with even small to medium-size rotator cuff tears. This fact cannot be fully explained by our current understanding of the anatomical insertions of the supraspinatus and infraspinatus. The purpose of this study was to reinvestigate the humeral insertions of these tendons. METHODS The study included 113 shoulders from sixty-four cadavers. The humeral insertion areas of the supraspinatus and infraspinatus were investigated in ninety-seven specimens. In sixteen specimens, all muscular portions of the supraspinatus and infraspinatus were removed, leaving the tendinous portions intact, in order to define the specific characteristics of the tendinous portion of the muscles. Another twenty-six shoulders were used to obtain precise measurements of the footprints of the supraspinatus and infraspinatus. RESULTS The supraspinatus had a long tendinous portion in the anterior half of the muscle, which always inserted into the anteriormost area of the highest impression on the greater tuberosity and which inserted into the superiormost area of the lesser tuberosity in 21% of the specimens. The footprint of the supraspinatus was triangular in shape, with an average maximum medial-to-lateral length of 6.9 mm and an average maximum anteroposterior width of 12.6 mm. The infraspinatus had a long tendinous portion in the superior half of the muscle, which curved anteriorly and extended to the anterolateral area of the highest impression of the greater tuberosity. The footprint of the infraspinatus was trapezoidal in shape, with an average maximum medial-to-lateral length of 10.2 mm and an average maximum anteroposterior width of 32.7 mm. CONCLUSIONS The footprint of the supraspinatus on the greater tuberosity is much smaller than previously believed, and this area of the greater tuberosity is actually occupied by a substantial amount of the infraspinatus.

Mesenchymal stem cells derived from synovium, meniscus, anterior cruciate ligament, and articular chondrocytes share similar gene expression profiles.

Mesenchymal stem cells (MSCs) can be obtained from various tissues, and contain common features. However, an increasing number of reports have described variant properties dependent of cell sources. We examined (1) whether MSCs existed in several intraarticular tissues, (2) whether gene expression profiles in intraarticular tissue MSCs closely resembled each other, and (3) whether identified genes were specific to intraarticular tissue MSCs. Human synovium, meniscus, intraarticular ligament, muscle, adipose tissue, and bone marrow were harvested, and colony‐forming cells were analyzed. All these cells showed multipotentiality and surface markers typical of MSCs. Gene profiles of intraarticular tissue MSCs and chondrocytes were closer to each other than those of extraarticular tissues MSCs. Among three characteristic genes specific for intraarticular tissue MSCs, we focused on proline arginine‐rich end leucine‐rich repeat protein (PRELP). Higher expression of PRELP was confirmed in chondrocytes and intraarticular tissue MSCs among three elderly and three young donors. Synovium MSCs stably expressed PRELP, contrarily, bone marrow MSCs increased PRELP expression during in vitro chondrogenesis. In conclusion, MSCs could be isolated from various intraarticular tissues including meniscus and ligament, gene expression profiles of intraarticular tissue MSCs closely resembled each other, and the higher expression of PRELP was characteristic of intraarticular tissue MSCs.

Synovial Stem Cells Are Regionally Specified According to Local Microenvironments After Implantation for Cartilage Regeneration

We previously demonstrated that synovium‐derived MSCs had greater in vitro chondrogenic ability than other mesenchymal tissues, suggesting a superior cell source for cartilage regeneration. Here, we transplanted undifferentiated synovium‐derived MSCs into a full‐thickness articular cartilage defect of adult rabbits and defined the cellular events to elucidate the mechanisms that govern multilineage differentiation of MSCs. Full‐thickness osteochondral defects were created in the knee; the defects were filled with 1,1′‐dioctadecyl‐3,3,3′,3′‐tetramethylindocarbocyanine perchlorate‐labeled MSCs and covered with periosteum. After 4 weeks, although the cell density decreased, transplanted MSCs produced a great amount of cartilage matrix extensively. The periosteum became thinner, and chondroprogenitors in the periosteum produced a small amount of cartilage matrix. In the deeper zone, transplanted MSCs progressed to the hypertrophic chondrocyte‐like cells. In the deep zone, some transplanted cells differentiated into bone cells and were replaced with host cells thereafter. In the next phase, the border between bone and cartilage moved upwards. In addition, integrations between native cartilage and regenerated tissue were improved. Chondrocyte‐like cells derived from the transplanted MSCs still remained at least after 24 weeks. Histological scores of the MSC group improved continuously and were always better than those of two other control groups. Immunohistological analyses and transmission electron microscopy confirmed that the MSCs produced abundant cartilage matrix. We demonstrated that transplanted synovium‐derived MSCs were altered over a time course according to the microenvironments. Our results will advance MSC‐based therapeutic strategies for cartilage injury and provide the clues for the mechanisms that govern multilineage differentiation of MSCs.

Local adherent technique for transplanting mesenchymal stem cells as a potential treatment of cartilage defect

IntroductionCurrent cell therapy for cartilage regeneration requires invasive procedures, periosteal coverage and scaffold use. We have developed a novel transplantation method with synovial mesenchymal stem cells (MSCs) to adhere to the cartilage defect.MethodsFor ex vivo analysis in rabbits, the cartilage defect was faced upward, filled with synovial MSC suspension, and held stationary for 2.5 to 15 minutes. The number of attached cells was examined. For in vivo analysis in rabbits, an autologous synovial MSC suspension was placed on the cartilage defect, and the position was maintained for 10 minutes to adhere the cells to the defect. For the control, either the same cell suspension was injected intra-articularly or the defects were left empty. The three groups were compared macroscopically and histologically. For ex vivo analysis in humans, in addition to the similar experiment in rabbits, the expression and effects of neutralizing antibodies for adhesion molecules were examined.ResultsEx vivo analysis in rabbits demonstrated that the number of attached cells increased in a time-dependent manner, and more than 60% of cells attached within 10 minutes. The in vivo study showed that a large number of transplanted synovial MSCs attached to the defect at 1 day, and the cartilage defect improved at 24 weeks. The histological score was consistently better than the scores of the two control groups (same cell suspension injected intra-articularly or defects left empty) at 4, 12, and 24 weeks. Ex vivo analysis in humans provided similar results to those in rabbits. Intercellular adhesion molecule 1-positive cells increased between 1 minute and 10 minutes, and neutralizing antibodies for intercellular adhesion molecule 1, vascular cell adhesion molecule 1 and activated leukocyte-cell adhesion molecule inhibited the attachment.ConclusionPlacing MSC suspension on the cartilage defect for 10 minutes resulted in adherence of >60% of synovial MSCs to the defect, and promoted cartilage regeneration. This adherent method makes it possible to adhere MSCs with low invasion, without periosteal coverage, and without a scaffold.

Increased proliferation of human synovial mesenchymal stem cells with autologous human serum: Comparisons with bone marrow mesenchymal stem cells and with fetal bovine serum

OBJECTIVE Synovial mesenchymal stem cells (MSCs) are a promising cell source for cartilage regeneration due to their high chondrogenic potential. For clinical safety, autologous human serum should be used instead of fetal bovine serum (FBS). We undertook this study to compare the 2 types of serum for their enhancement of the proliferation and chondrogenic potentials of synovial MSCs and to investigate the mechanisms of the differences. Since effectiveness of the sera might depend on the origin of the MSCs, we also examined bone marrow MSCs. METHODS Synovium, bone marrow, and peripheral blood were obtained from 18 donors. Synovial and bone marrow MSCs were cultured with autologous human serum or FBS and analyzed. In addition, rabbit synovial MSCs cultured with autologous serum or FBS were transplanted into full-thickness cartilage defects of the knees of the same rabbits. RESULTS Human synovial MSCs expanded more in human serum than in FBS, and the opposite results were obtained with bone marrow MSCs. Hierarchical clustering analysis showed that the cell source, rather than the type of serum, affected the gene expression profile. Human serum contained high levels of platelet-derived growth factor (PDGF), synovial MSCs expressed higher levels of PDGF receptor alpha than did bone marrow MSCs, and neutralizing PDGF decreased the proliferation of synovial MSCs with autologous human serum. Although the in vitro chondrogenic potential of human synovial MSCs was affected by the serum source, the in vivo chondrogenic potential of rabbit synovial MSCs was similar in autologous serum and FBS groups. CONCLUSION Autologous serum predominates in increasing the proliferation of synovial MSCs with chondrogenic potential through PDGF signaling.

Synovial fluid-derived mesenchymal stem cells increase after intra-articular ligament injury in humans

OBJECTIVE The existence of mesenchymal stem cells (MSCs) in SF was previously reported. However, the behaviour and properties of MSCs derived from SF have not been fully elucidated. METHODS Human SFs were obtained from 19 knee joints with anterior cruciate ligament injury around the time of reconstruction surgery, and from three healthy volunteers. SF was plated, cultured and examined for colony-forming number, in vitro differentiation, surface epitopes and gene profiles. Also, rabbit synovium-MSCs were injected into the knee joint in a rabbit partial anterior cruciate ligament defect model, and the injected cells were traced. RESULTS SF-MSCs from IA ligament injury patients were 100 times more in number than those from healthy volunteers. Total colony number was positively correlated with post-injury period. No significant differences were observed among the cells derived from SF around the time of the surgery in relation to surface epitopes and differentiation potentials. Cluster analysis of gene profiles demonstrated that SF-MSCs were more similar to synovium MSCs than bone marrow MSCs. In rabbit experiments, the MSCs injected into the knee in which IA ligament was partially defective were observed more on the defected area than on the intact area of the ligament at 24 h. CONCLUSION We demonstrated that SF-MSCs, similar to synovium MSCs, increased in number after IA ligament injury and surgery without marked alteration of the properties.

Subscapularis Tendon Tear: An Anatomic and Clinical Investigation

PURPOSE The purpose of this study was to clarify anatomically and clinically how the subscapularis tendon supports the superior portion of the biceps tendon to the intertubercular groove. METHODS Thirty-three embalmed shoulder girdles were examined to investigate the subscapularis tendon and the pathway of the biceps tendon. In addition, operation records of 435 consecutive arthroscopic rotator cuff repairs were retrospectively reviewed. RESULTS Anatomically, the superior-most insertion of the subscapularis tendon was located on the upper margin of the lesser tuberosity. In addition, a thin tendinous slip extended from the insertion and attached to the fovea capitis of the humerus. The insertion, the tendinous slip, and the lateral portion of the cranial part of intramuscular tendons were in direct contact with the inferior side of the biceps tendon at its corner portion. The clinical study showed that 27.4% of rotator cuff tears (119/435) had subscapularis tendon tears. In cases with an unstable biceps tendon there was no intact subscapularis tendon. The superior-most insertion of the subscapularis tendon was involved in all transverse tears. Of 29 full-thickness transverse tears, 13 (44.8%) showed intra-articular dislocation. CONCLUSIONS The trochlea-like structure was composed of the superior-most insertion, the tendinous slip, and the lateral portion of the cranial part of intramuscular tendons supporting the biceps tendon. The transverse tear of the subscapularis tendon, which included this trochlea-like structure, often leads to intra-articular dislocation of the biceps tendon. CLINICAL RELEVANCE Instability of the biceps tendon should be carefully assessed because it is associated with subscapularis tendon tears at a very high incidence. When we repair a transverse tear of the subscapularis tendon, we should widely fix sufficiently strong tissue to support the biceps tendon on the uppermost margin, not on the anteromedial portion, of the lesser tuberosity.

Anatomy of Normal Human Anterior Cruciate Ligament Attachments Evaluated by Divided Small Bundles

Background Double-bundle anterior cruciate ligament (ACL) reconstruction has several potential advantages over single-bundle reconstruction with hamstring tendons. However, there are still controversies regarding tunnel placement in tibial and femoral attachments. Hypothesis The macroscopically normal ACL consists of small bundles about 1 mm in diameter. Detailed observation of the divided smaller bundles will achieve better understanding of the tunnel placement in anatomic ACL reconstruction. Study Design Descriptive laboratory study. Methods This study used 20 cadaveric knees. The ACL was divided into anteromedial and posterolateral bundles, then separated into 10 small bundles of 2-mm diameters, with preservation of their attachment sites marked with color markers. The positional relationship between the femoral and tibial attachments of each small bundle was investigated. Results A layered positional correlation of small bundles was found between the tibial and femoral attachments. Small bundles aligned in the anterior-posterior direction in the tibia corresponded to the bundles aligned in a high-low direction in the femur in flexion. The femoral attachment pattern was relatively similar in each specimen; however, the tibial attachment showed 2 patterns: an oblique type (12 of 20) and a transverse type (8 of 20). The posterior portion of the posterolateral bundle was separately attached to the medial and lateral portions of the tibial attachment. There was no fibrous insertion in the center of the posterior portion of the ACL tibial attachment in any specimen. In this bare area, there was fat tissue and vascular bundles. Conclusion Small bundles constituting the ACL showed a relatively layered arrangement between 2 attachments. The tibial attachment showed 2 patterns of oblique and transverse types, and the vascular bundles were located in the center of the posterolateral bundle. Clinical Relevance The results of this study of the normal ACL will provide insights for surgeons when placing grafts during anatomic ACL reconstruction.