Yoshiyasu Uchiyama

A Radiographic Classification of Massive Rotator Cuff Tear Arthritis

BackgroundIn 1990, Hamada et al. radiographically classified massive rotator cuff tears into five grades. Walch et al. subsequently subdivided Grade 4 to reflect the presence/absence of subacromial arthritis and emphasize glenohumeral arthritis as a characteristic of Grade 4.Questions/purposesWe therefore determined (1) whether patient characteristics and MRI findings differed between the grades at initial examination and final followup; (2) which factors affected progression to a higher grade; (3) whether the retear rate of repaired tendons differed among the grades; and (4) whether the radiographic grades at final followup differed from those at initial examination among patients treated operatively.Patients and MethodsWe retrospectively reviewed 75 patients with massive rotator cuff tears. Thirty-four patients were treated nonoperatively and 41 operatively.ResultsPatients with Grade 3, 4, or 5 tears had a higher incidence of fatty muscle degeneration of the subscapularis muscle than patients with Grade 1 or 2 tears. In 26 patients with Grade 1 or 2 tears at initial examination, duration of followup was longer in patients who remained at Grade 1 or 2 than in those who progressed to Grade 3, 4, or 5 at final followup. The retear rate of repaired supraspinatus tendon was more frequent in Grade 2 than Grade 1 tears. In operated cases, radiographic grades at final followup did not develop to Grades 3 to 5.ConclusionsWe believe cuff repair should be performed before acromiohumeral interval narrowing. Our observations are consistent with the temporal concepts of massive cuff tear pathomechanics proposed by Burkhart and Hansen et al.Level of EvidenceLevel III, Therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Functional Recovery of Damaged Skeletal Muscle Through Synchronized Vasculogenesis, Myogenesis, and Neurogenesis by Muscle-Derived Stem Cells

Background— Recent studies have shown that skeletal muscle–derived stem cells (MDSCs) can give rise to several cell lineages after transplantation. However, the potential therapeutic uses of MDSCs, the functional significance of the transplanted tissue, and vasculogenesis, myogenesis, and reconstitution of other tissues have yet to be investigated in detail. In addition, the relationship between MDSCs and mesenchymal bone marrow cells is of interest. Methods and Results— We developed a severe-damage model of mouse tibialis anterior muscle with a large deficit of nerve fibers, muscle fibers, and blood vessels. We investigated the potential therapeutic use of freshly isolated CD34+/45− (Sk-34) cells. Results showed that, after transplantation, implanted cells give rise to myogenic, vascular (pericytes, vascular smooth muscle cells, and endothelial cells), and neural (Schwann) cells, as well as contributing to the synchronized reconstitution of blood vessels, muscle fibers, and peripheral nerves, with significant recovery of both mass and contractile function after transplantation. Investigation of Sk-34 cell transplantation to the renal capsule (nonmuscle tissue) and fluorescence in situ hybridization analysis for the transplanted muscle detecting the Y chromosome revealed the intrinsic plasticity of the Sk-34 cell population. In addition, there were no donor-derived Sk-34 cells in the muscle of lethally irradiated bone marrow–transplanted animals, indicating that the Sk-34 cells were not derived from bone marrow. Conclusions— These findings indicate that freshly isolated skeletal muscle–derived Sk-34 cells are potentially useful for reconstitution therapy of the vascular, muscular, and peripheral nervous systems. These results provide new insights into somatic stem and/or progenitor cells with regard to vasculogenesis, myogenesis, and neurogenesis.

Clonal multipotency of skeletal muscle-derived stem cells between mesodermal and ectodermal lineage.

The differentiation potential of skeletal muscle‐derived stem cells (MDSCs) after in vitro culture and in vivo transplantation has been extensively studied. However, the clonal multipotency of MDSCs has yet to be fully determined. Here, we show that single skeletal muscle‐derived CD34−/CD45− (skeletal muscle‐derived double negative [Sk‐DN]) cells exhibit clonal multipotency that can give rise to myogenic, vasculogenic, and neural cell lineages after in vivo single cell‐derived single sphere implantation and in vitro clonal single cell culture. Muscles from green fluorescent protein (GFP) transgenic mice were enzymatically dissociated and sorted based on CD34 and CD45. Sk‐DN cells were clone‐sorted into a 96‐well plate and were cultured in collagen‐based medium with basic fibroblast growth factor and epidermal growth factor for 14 days. Individual colony‐forming units (CFUs) were then transplanted directly into severely damaged muscle together with 1 × 105 competitive carrier Sk‐DN cells obtained from wild‐type mice muscle expanded for 5 days under the same culture conditions using 35‐mm culture dishes. Four weeks after transplantation, implanted GFP+ cells demonstrated differentiation into endothelial, vascular smooth muscle, skeletal muscle, and neural cell (Schwann cell) lineages. This multipotency was also confirmed by expression of mRNA markers for myogenic (MyoD, myf5), neural (Musashi‐1, Nestin, neural cell adhesion molecule‐1, peripheral myelin protein‐22, Nucleostemin), and vascular (α‐smooth muscle actin, smoothelin, vascular endothelial‐cadherin, tyrosine kinase‐endothelial) stem cells by clonal (single‐cell derived) single‐sphere reverse transcription‐polymerase chain reaction. Approximately 70% of clonal CFUs exhibited expression of all three cell lineages. These findings support the notion that Sk‐DN cells are a useful tool for damaged muscle‐related tissue reconstitution by synchronized vasculogenesis, myogenesis, and neurogenesis.

Cardiomyocyte Formation by Skeletal Muscle-Derived Multi-Myogenic Stem Cells after Transplantation into Infarcted Myocardium

BACKGROUND Cellular cardiomyoplasty for myocardial infarction has been developed using various cell types. However, complete differentiation and/or trans-differentiation into cardiomyocytes have never occurred in these transplant studies, whereas functional contributions were reported. METHODS AND RESULTS Skeletal muscle interstitium-derived CD34(+)/CD45(-) (Sk-34) cells were purified from green fluorescent protein transgenic mice by flowcytometory. Cardiac differentiation of Sk-34 cells was examined by in vitro clonal culture and co-culture with embryonic cardiomyocytes, and in vivo transplantation into a nude rat myocardial infarction (MI) model (left ventricle). Lower relative expression of cardiomyogenic transcription factors, such as GATA-4, Nkx2-5, Isl-1, Mef2 and Hand2, was seen in clonal cell culture. However, vigorous expression of these factors was seen on co-culture with embryonic cardiomyocytes, together with formation of gap-junctions and synchronous contraction following sphere-like colony formation. At 4 weeks after transplantation of freshly isolated Sk-34 cells, donor cells exhibited typical cardiomyocyte structure with formation of gap-junctions, as well as intercalated discs and desmosomes, between donor and recipient and/or donor and donor cells. Fluorescence in situ hybridization (FISH) analysis detecting the rat and mouse genomic DNA and immunoelectron microscopy using anti-GFP revealed donor-derived cells. Transplanted Sk-34 cells were incorporated into infarcted portions of recipient muscles and contributed to cardiac reconstitution. Significant improvement in left ventricular function, as evaluated by transthoracic echocardiography and micro-tip conductance catheter, was also observed. CONCLUSIONS AND SIGNIFICANCE Skeletal muscle-derived multipotent Sk-34 cells that can give rise to skeletal and smooth muscle cells as reported previously, also give rise to cardiac muscle cells as multi-myogenic stem cells, and thus are a potential source for practical cellular cardiomyoplasty.

Skeletal Muscle-Derived CD34 + /45 - and CD34 - /45 - Stem Cells Are Situated Hierarchically Upstream of Pax7 + Cells

The hierarchical relationship of skeletal muscle-derived multipotent stem cells sorted as CD34(+)/CD45(-) (Sk-34) and CD34(-)/CD45(-) (Sk-DN) cells, which have synchronized reconstitution capacities for blood vessels, peripheral nerves, and muscle fibers, was examined. Expression of Sca-1 and CD34 (typical state of freshly isolated Sk-34 cells) in Sk-DN cells was examined using in vitro culture and in vivo cell implantation. Sk-DN cells sequentially expressed Sca-1 and CD34 during cell culture showing self-maintenance and/or self-renewal-like behavior, and are thus considered hierarchically upstream of Sk-34 cells in the same lineage. Sk-34 and Sk-DN cells were further divided into small and large cell fractions by cell sorting. Immunocytochemistry using anti-Pax7 was performed at the time of isolation (before culture) and revealed that only 1% of cells in the large Sk-DN cell fraction were positive for Pax7, while Sk-34 cells and 99% of Sk-DN cells were negative for Pax7. Therefore, putative satellite cells were possibly present in the large Sk-DN cell fraction. However, serial analysis of Pax7 expression by RT-PCR and immunocytochemistry for single and 2 to >40 clonally proliferated Sk-34 and Sk-DN cells revealed that both cell types expressed Pax7 after several asymmetric cellular divisions during clonal-cell culture. In addition, production of satellite cells was seen after muscle fiber formation following Sk-34 or Sk-DN cell transplantation into damaged muscle, and even in the nonmuscle tissue environment (beneath the renal capsule). Thus, Sk-DN cells are situated upstream of Sk-34 cells and both cells can produce Pax7+ cells (putative satellite cells) after cellular division.

Preferential and Comprehensive Reconstitution of Severely Damaged Sciatic Nerve Using Murine Skeletal Muscle-Derived Multipotent Stem Cells

Loss of vital functions in the somatic motor and sensory nervous systems can be induced by severe peripheral nerve transection with a long gap following trauma. In such cases, autologous nerve grafts have been used as the gold standard, with the expectation of activation and proliferation of graft-concomitant Schwann cells associated with their paracrine effects. However, there are a limited number of suitable sites available for harvesting of nerve autografts due to the unavoidable sacrifice of other healthy functions. To overcome this problem, the potential of skeletal muscle-derived multipotent stem cells (Sk-MSCs) was examined as a novel alternative cell source for peripheral nerve regeneration. Cultured/expanded Sk-MSCs were injected into severely crushed sciatic nerve corresponding to serious neurotmesis. After 4 weeks, engrafted Sk-MSCs preferentially differentiated into not only Schwann cells, but also perineurial/endoneurial cells, and formed myelin sheath and perineurium/endoneurium, encircling the regenerated axons. Increased vascular formation was also observed, leading to a favorable blood supply and waste product excretion. In addition, engrafted cells expressed key neurotrophic and nerve/vascular growth factor mRNAs; thus, endocrine/paracrine effects for the donor/recipient cells were also expected. Interestingly, skeletal myogenic capacity of expanded Sk-MSCs was clearly diminished in peripheral nerve niche. The same differentiation and tissue reconstitution capacity of Sk-MSCs was sufficiently exerted in the long nerve gap bridging the acellular conduit, which facilitated nerve regeneration/reconnection. These effects represent favorable functional recovery in Sk-MSC-treated mice, as demonstrated by good corduroy walking. We also demonstrated that these differentiation characteristics of the Sk-MSCs were comparable to native peripheral nerve-derived cells, whereas the therapeutic capacities were largely superior in Sk-MSCs. Therefore, Sk-MSCs can be a novel/suitable alternative cell source for healthy nerve autografts.

Surgical treatment of confirmed intratendinous rotator cuff tears: Retrospective analysis after an average of eight years of follow-up

HYPOTHESIS This study evaluated clinical features, diagnostic techniques, and summarized the results of open repair in a series of surgically confirmed cases of intratendinous rotator cuff tears. MATERIALS AND METHODS Between 1986 and 1999, 19 patients (17 men and 2 women) with intratendinous rotator cuff tears underwent surgery. Clinical findings, diagnostic results, and surgical findings were evaluated. The shoulder scores of the Japanese Orthopaedic Association (JOA) and the American Shoulder and Elbow Surgeons (ASES) were used to assess recovery at an average of 92 months (range, 31-231 months). RESULTS All patients had symptoms consistent with rotator cuff tendonitis. History of overt trauma was noted in 16 (84.2%). Neither ultrasound nor magnetic resonance imaging proved reliable for preoperative diagnosis. Surgery was performed if at least 6 months of conservative treatment, such as rest, heat, and physical therapies, failed. The definitive diagnosis was established intraoperatively with a longitudinal split along the fibers of the supraspinatus tendon. None of the intratendinous lesions had communication to the subacromial bursa or the glenohumeral joint. Excision of the intratendinous tear and repair resulted in improvement in pain and total scores of both JOA (66.8 vs 94.1) and ASES (37.1 vs 91.0). CONCLUSIONS Intratendinous rotator cuff tears were difficult to diagnose preoperatively. Our data suggest that conservative treatment failed, anterior acromioplasty and excision of the diseased portion of the tendon, followed by tenorrhaphy, proved effective. Satisfactory outcomes were achieved in 18 patients (94.7%) in this series.

Clinical results of a surgical technique using endobuttons for complete tendon tear of pectoralis major muscle: report of five cases

BackgroundWe herein describe a surgical technique for the repair of complete tear of the pectoralis major (PM) tendon using endobuttons to strengthen initial fixation.MethodsFive male patients (3 judo players, 1 martial arts player, and 1 body builder) were treated within 2 weeks of sustaining complete tear of the PM tendon. Average age at surgery and follow-up period were 28.4 years (range, 23-33) and 28.8 months (range, 24-36). A rectangular bone trough (about 1 × 4 cm) was created on the humerus at the insertion of the distal PM tendon. The tendon stump was introduced into this trough, and fixed to the reverse side of the humeral cortex using endobuttons and non-absorbable suture. Clinical assessment of re-tear was examined by MRI. Shoulder range of motion (ROM), outcome of treatment, and isometric power were measured at final follow-up.ResultsThere were no clinical re-tears, and MRI findings also showed continuity of the PM tendon in all cases at final follow-up. Average ROM did not differ significantly between the affected and unaffected shoulders. The clinical outcomes at final follow-up were excellent (4/5 cases) or good (1/5). In addition, postoperative isometric power in horizontal flexion of the affected shoulder showed complete recovery when compared with the unaffected side.ConclusionsSatisfactory outcomes could be obtained when surgery using the endobutton technique was performed within 2 weeks after complete tear of the PM tendon. Therefore, our new technique appears promising as a useful method to treat complete tear of the PM tendon.

Anabolic-androgenic steroid does not enhance compensatory muscle hypertrophy but significantly diminish muscle damages in the rat surgical ablation model

Cellular responses in the compensatory hypertrophied (plantaris) muscle induced by surgical ablation of synergistic muscles (soleus and gastrocnemius) were determined during 10-week anabolic androgenic steroid (AAS) treatment. Adult Wistar male rats were divided randomly into the Control and Steroid groups, and contralateral surgery was performed. Nandrolone decanoate was administered to the Steroid group. [3H]thymidine and [14C]leucine labeling were used to determine the serial changes in cellular mitotic activity and amino acid uptake. Myogenic cells and cellular responses in blood vessels and nerve fibers were analyzed by immunohistochemistry. Significantly lower cellular mitotic activity associated with lower volume of muscle fiber necrosis was observed in the Steroid group during the first week. However, amino acid uptake and final muscle wet weight gain did not differ between the groups. Marked activation/proliferation of muscular, vascular, and peripheral nerve-related cells was seen with the inflammatory responses in both groups. However, this activation was dependent on the volume of muscle fiber damage and was not preferentially accelerated by AAS loading. These results indicated that AAS loading significantly diminished muscle fiber damages, but they did not accelerate final muscle wet weight gain and activation of myogenic, vascular, and peripheral nerve related cells in the compensatory enlarged muscles.

Clonal Differentiation of Skeletal Muscle–Derived CD34−/45− Stem Cells Into Cardiomyocytes In Vivo

The differentiation and/or therapeutic potential of skeletal muscle-derived stem cells for cardiac infarction have been studied extensively for use in cellular cardiomyoplasty, as injured cardiomyocytes exhibit limited regenerative capacity. We previously reported cardio-myogenic differentiation of skeletal muscle-derived CD34+/45(-) (Sk-34) stem cells after therapeutic transplantation. However, the clonal differentiation potential of these cells remains unknown. Here, we show that skeletal muscle-derived CD34(-)/45(-) (Sk-DN) stem cells, which are situated upstream of Sk-34 cells in the same lineage, exhibit clonal differentiation into cardiomyocytes after single cell-derived single-sphere implantation into myocardium. Sk-DN cells were enzymatically isolated from green fluorescent protein (GFP) transgenic mice and purified by flow cytometry, and were then clonally cultured in collagen-based medium with bFGF and EGF after clonal cell sorting. Single cell-derived single-sphere colonies of Sk-DN cells were directly implanted into the wild-type mouse myocardium. At 4 weeks after implantation, donor cells exhibited typical cardiomyocyte structure with the formation of gap-junctions between donor and recipient cells. Expression of specific mRNAs for cardiomyocytes, such as cardiac actin and GATA-4, Nkx2-5, Isl-1, Mef2, and Hand2, were also seen in clonal cell cultures of Sk-DN cells. Cell fusion-independent differentiation was also confirmed by bulk cell transplantation using Cre- and loxP (enhanced GFP)-mice. We conclude that Sk-DN cells can give rise to cardiac muscle cells clonally, and that skeletal muscle includes a practical cell source for cellular cardiomyoplasty.