Oversulfated chondroitin/dermatan sulfates containing GlcAbeta1/IdoAalpha1-3GalNAc(4,6-O-disulfate) interact with L- and P-selectin and chemokines

We previously reported that versican, a large chondroitin/dermatan sulfate (CS/DS) proteoglycan, interacts through its CS/DS chains with adhesion molecules L- and P-selectin and CD44, as well as chemokines. Here, we have characterized these interactions further. Using a metabolic inhibitor of sulfation, sodium chlorate, we show that the interactions of the CS/DS chains of versican with L- and P-selectin and chemokines are sulfation-dependent but the interaction with CD44 is sulfation-independent. Consistently, versican's binding to L- and P-selectin and chemokines is specifically inhibited by oversulfated CS/DS chains containing GlcAbeta1-3GalNAc(4,6-O-disulfate) or IdoAalpha1-3GalNAc(4,6-O-disulfate), but its binding to CD44 is inhibited by all the CS/DS chains, including low-sulfated and unsulfated ones. Affinity and kinetic analyses using surface plasmon resonance revealed that the oversulfated CS/DS chains containing GlcAbeta1/IdoAalpha1-3GalNAc(4,6-O-disulfate) bind directly to selectins and chemokines with high affinity (K(d) 21.1 to 293 nm). In addition, a tetrasaccharide fragment of repeating GlcAbeta1-3GalNAc(4,6-O-disulfate) units directly interacts with L- and P-selectin and chemokines and oversulfated CS/DS chains containing GlcAbeta1/IdoAalpha1-3GalNAc(4,6-O-disulfate) inhibit chemokine-induced Ca(2+) mobilization. Taken together, our results show that oversulfated CS/DS chains containing GlcAbeta1/IdoAalpha1-3GalNAc(4,6-O-disulfate) are recognized by L- and P-selectin and chemokines, and imply that these chains are important in selectin- and/or chemokine-mediated cellular responses.

Binding of a large chondroitin sulfate/dermatan sulfate proteoglycan, versican, to L-selectin, P-selectin, and CD44

Here we show that a large chondroitin sulfate proteoglycan, versican, derived from a renal adenocarcinoma cell line ACHN, binds L-selectin, P-selectin, and CD44. The binding was mediated by the interaction of the chondroitin sulfate (CS) chain of versican with the carbohydrate-binding domain of L- and P-selectin and CD44. The binding of versican to L- and P-selectin was inhibited by CS B, CS E, and heparan sulfate (HS) but not by any other glycosaminoglycans tested. On the other hand, the binding to CD44 was inhibited by hyaluronic acid, chondroitin (CH), CS A, CS B, CS C, CS D, and CS E but not by HS or keratan sulfate. A cross-blocking study indicated that L- and P-selectin recognize close or overlapping sites on versican, whereas CD44 recognizes separate sites. We also show that soluble L- and P-selectin directly bind to immobilized CS B, CS E, and HS and that soluble CD44 directly binds to immobilized hyaluronic acid, CH, and all the CS chains examined. Consistent with these results, structural analysis showed that versican is modified with at least CS B and CS C. Thus, proteoglycans sufficiently modified with the appropriate glycosaminoglycans should be able to bind L-selectin, P-selectin, and/or CD44.

Versican interacts with chemokines and modulates cellular responses

We previously reported that versican, a large chondroitin sulfate proteoglycan, isolated from a renal adenocarcinoma cell line, ACHN, binds L-selectin. Here we report that versican also binds certain chemokines and regulates chemokine function. This binding was strongly inhibited by the chondroitinase digestion of versican or by the addition of soluble chondroitin sulfate (CS) B, CS E, or heparan sulfate. Furthermore, these glycosaminoglycans (GAGs) could bind directly to the chemokines that bind versican. Thus, versican appears to interact with chemokines via its GAGs. We next examined if versican or GAGs affect secondary lymphoid tissue chemokine (SLC)-induced integrin activation and Ca(2+) mobilization in lymphoid cells expressing a receptor for SLC, CC chemokine receptor 7. Interestingly, whereas heparan sulfate supported both alpha(4)beta(7) integrin-dependent binding to mucosal addressin cell adhesion molecule-1 (MAdCAM-1)-IgG and Ca(2+) mobilization induced by SLC, versican or CS B inhibited these cellular responses, and the extent of inhibition was dependent on the dose of versican or CS B added. These findings suggest that different proteoglycans have different functions in the regulation of chemokine activities and that versican may negatively regulate the function of SLC via its GAG chains.

Prediction of acute coronary syndromes by percutaneous coronary angioscopy in patients with stable angina

To pinpoint the link between plaque characteristics and acute coronary syndromes, we performed a 12-month prospective follow-up study in 157 patients with stable angina pectoris in whom regular coronary plaques were observed by percutaneous coronary angioscopy. Acute coronary syndromes occurred more frequently in patients with yellow plaque than in those with white plaques (11 of 39 vs 4 of 118; p = 0.00021). Moreover, the syndromes occurred more frequently in patients with glistening yellow plaques than in those with nonglistening yellow plaques (9 of 13 vs 2 of 26; p = 0.00026). Thrombus arising from the ruptured identical plaques was confirmed by angioscopy as the culprit lesion of the syndromes. The results indicate that acute coronary syndromes occur frequently and in a short time in patients with glistening yellow plaques and that angioscopy but not angiography is feasible for prediction of the syndromes.

Derivation of 2 categories of plasmacytoid dendritic cells in murine bone marrow

Plasmacytoid dendritic cells (pDCs) competent to make type I interferon were rigorously defined as a Ly-6C(+) and CD11c(Lo) subset of the B220(+)CD19(-) CD43(+)CD24(Lo) bone marrow (BM) Fraction A. Otherwise similar Ly6C(-) cells expressed the natural killer (NK) markers DX5 and NK1.1. pDCs represented a stable, discrete, and long-lived population. Stem cells and early lymphoid progenitors (ELPs), but not prolymphocytes, were effective precursors of pDCs, and their differentiation was blocked by ligation of Notch receptors. Furthermore, pDCs were present in the BM of RAG1(-/-), CD127/IL-7Ra(-/-), and Pax5(-/-) mice. pDCs in RAG1/GFP knock-in mice could be subdivided, and immunoglobulin D(H)-J(H) rearrangements, as well as transcripts for the B-lineage-related genes Pax5, mb1/CD79a, ebf, and Bcl11a, were identified only in the green fluorescent protein-positive (GFP(+)) pDC1 subset. All pDCs expressed terminal deoxynucleotidyl transferase (TdT), the ETS transcription factor Spi-B, the nuclear factor-kappaB transcription factor RelB, toll-like receptor 9 (TLR9), and interferon consensus sequence binding protein (ICSBP)/interferon regulatory factor 8 (IRF-8) transcripts; lacked CD16 and granulocyte colony-stimulating factor receptor (G-CSFR); and were uniformly interleukin-7 receptor alpha (IL-7Ralpha(-)) AA4.1(Lo), CD27(-), Flk-2(Lo), c-Kit(-), DX-5(-), and CD11b(-), while CD4 and CD8alpha were variable. GFP(+) pDC1 subset was less potent than GFP(-) pDC2s in T allostimulation and production of tumor necrosis factor alpha (TNFalpha), interferon alpha (IFNalpha), and interleukin-6 (IL-6), while only pDC2s made IFNgamma and IL-12 p70. Thus, 2 functionally specialized subsets of pDCs arise in bone marrow from progenitors that diverge from B, T, and NK lineages at an early stage.

Liver metastases from colorectal cancers: detection with CT during arterial portography

A total of 45 metastases to the liver from colorectal cancer were resected in 22 patients. The detectability of these lesions with the following modalities was determined: real-time ultrasound (US), computed tomography (CT), selective celiac arteriography (SCA), infusion hepatic angiography (IHA), CT during arterial portography (CTAP), and CT following intraarterial injection of iodized poppyseed oil (Lipiodol). The total detection rate (sensitivity) was 58% for US, 63% for CT, 27% for SCA, 50% for IHA, 84% for CTAP, and 38% for CT with iodized oil. Ten of 18 lesions less than 15 mm in largest diameter were demonstrated preoperatively by CTAP only. CTAP is useful in clarifying the locations of the lesions in the liver and should always be performed before liver metastases from colorectal cancer are resected.

Gene components responsible for discrete substrate specificity in the metabolism of biphenyl (bph operon) and toluene (tod operon)

bph operons coding for biphenyl-polychlorinated biphenyl degradation in Pseudomonas pseudoalcaligenes KF707 and Pseudomonas putida KF715 and tod operons coding for toluene-benzene metabolism in P. putida F1 are very similar in gene organization as well as size and homology of the corresponding enzymes (G. J. Zylstra and D. T. Gibson, J. Biol. Chem. 264:14940-14946, 1989; K. Taira, J. Hirose, S. Hayashida, and K. Furukawa, J. Biol. Chem. 267:4844-4853, 1992), despite their discrete substrate ranges for metabolism. The gene components responsible for substrate specificity between the bph and tod operons were investigated. The large subunit of the terminal dioxygenase (encoded by bphA1 and todC1) and the ring meta-cleavage compound hydrolase (bphD and todF) were critical for their discrete metabolic specificities, as shown by the following results. (i) Introduction of todC1C2 (coding for the large and small subunits of the terminal dioxygenase in toluene metabolism) or even only todC1 into biphenyl-utilizing P. pseudoalcaligenes KF707 and P. putida KF715 allowed them to grow on toluene-benzene by coupling with the lower benzoate meta-cleavage pathway. Introduction of the bphD gene (coding for 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase) into toluene-utilizing P. putida F1 permitted growth on biphenyl. (ii) With various bph and tod mutant strains, it was shown that enzyme components of ferredoxin (encoded by bphA3 and todB), ferredoxin reductase (bphA4 and todA), and dihydrodiol dehydrogenase (bphB and todD) were complementary with one another. (iii) Escherichia coli cells carrying a hybrid gene cluster of todClbphA2A3A4BC (constructed by replacing bphA1 with todC1) converted toluene to a ring meta-cleavage 2-hydroxy-6-oxo-hepta-2,4-dienoic acid, indicating that TodC1 formed a functional multicomponent dioxygenase associated with BphA2 (a small subunit of the terminal dioxygenase in biphenyl metabolism), BphA3, and BphA4.

Endoplasmic reticulum stress-induced apoptosis contributes to articular cartilage degeneration via C/EBP homologous protein

OBJECTIVE

When endoplasmic reticulum (ER) stress, i.e., the excessive accumulation of unfolded proteins in ER, endangers homeostasis, apoptosis is induced by C/EBP homologous protein (Chop). In osteoarthritis (OA) cartilage, Chop expression and apoptosis increase as degeneration progresses. We investigated the role of Chop in murine chondrocyte apoptosis and in the progression of cartilage degeneration.

METHOD

We induced experimental OA in Chop-knockout (Chop(-/-)) mice by medial collateral ligament transection and meniscectomy and compared cartilage degeneration, apoptosis, and ER stress in Chop(-/-)- and wild-type (Chop(+/+)) mice. In our in vitro experiments we treated murine Chop(-/-) chondrocytes with the ER stress inducer tunicamycin (TM) and evaluated apoptosis, ER stress, and chondrocyte function.

RESULTS

In vivo, the degree of ER stress was similar in Chop(-/-)- and Chop(+/+) mice. However, in Chop(-/-) mice apoptosis and cartilage degeneration were lower by 26.4% and 42.4% at 4 weeks, by 26.8% and 44.9% at 8 weeks, and by 26.9% and 32.3% at 12 weeks after surgery than Chop(+/+) mice, respectively. In vitro, the degree of ER stress induction by TM was similar in Chop(-/-)- and Chop(+/+) chondrocytes. On the other hand, apoptosis was 55.3% lower and the suppression of collagen type II and aggrecan mRNA was 21.0% and 23.3% less, and the increase of matrix metalloproteinase-13 mRNA was 20.0% less in Chop(-/-)- than Chop(+/+) chondrocytes.

CONCLUSION

Our results indicate that Chop plays a direct role in chondrocyte apoptosis and that Chop-mediated apoptosis contributes to the progression of cartilage degeneration in mice.

Epigenetic regulation of osteoclast differentiation: possible involvement of Jmjd3 in the histone demethylation of Nfatc1

Gene expression is controlled by epigenetic mechanisms such as histone acetylation and methylation, and recent studies have revealed that key developmental steps are regulated by the trimethylation of histone H3 lysine 4 (H3K4me3) and lysine 27 (H3K27me3). Using ChIP sequencing technology combined with real-time PCR, we here demonstrate that the H3K27me3 observed in the Nfatc1 gene in bone marrow-derived macrophages (BMMs) was markedly reduced in mature osteoclasts. Jumonji domain-containing 3 (Jmjd3), a H3K27 demethylase, was induced in bone marrow-derived macrophages and in the vicinity of the transcription start site (TSS) of nuclear factor-activated T cells (NFAT) c1 in response to receptor activator of nuclear factor-κB ligand (RANKL) stimulation. Gene silencing of the Jmjd3 gene by short hairpin RNA reduced demethylation of H3K27me3 at the TSS of Nfatc1 and suppressed RANKL-induced osteoclastogenesis. These results suggest that the demethylation of H3K27me3 in the Nfatc1 gene locus by Jmjd3 plays a critical role in RANKL-induced osteoclast differentiation.

Regulation of RANKL-induced osteoclastogenesis by TGF-β through molecular interaction between Smad3 and Traf6

Previous studies have shown that transforming growth factor β (TGF-β) promotes receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. However, the underlying molecular mechanisms have not been elucidated. When TGF-β signals were blocked either by a specific inhibitor of TGF-β type 1 receptor kinase activity, SB431542, or by introducing a dominant-negative mutant of TGF-β type 2 receptor, RANKL-induced osteoclastogenesis was almost completely suppressed. Blockade of Smad signaling by overexpression of Smad7 or c-Ski markedly suppressed RANKL-induced osteoclastogenesis, and retroviral induction of an activated mutant of Smad2 or Smad3 reversed the inhibitory effect of SB431542. Immunoprecipitation analysis revealed that Smad2/3 directly associates with the TRAF6-TAB1-TAK1 molecular complex, which is generated in response to RANKL stimulation and plays an essential role in osteoclast differentiation. TRAF6-TAB1-TAK1 complex formation was not observed when TGF-β signaling was blocked. Analysis using deletion mutants revealed that the MH2 domain of Smad3 is necessary for TRAF6-TAB1-TAK1 complex formation, downstream signal transduction, and osteoclast formation. In addition, gene silencing of Smad3 in osteoclast precursors markedly suppressed RANKL-induced osteoclast differentiation. In summary, TGF-β is indispensable in RANKL-induced osteoclastogenesis, and the binding of Smad3 to the TRAF6-TAB1-TAK1 complex is crucial for RANKL-induced osteoclastogenic signaling.

Enhanced apoptotic and reduced protective response in chondrocytes following endoplasmic reticulum stress in osteoarthritic cartilage

Endoplasmic reticulum (ER) stress has been shown to participate in many disease pathologies. Although recent reports have demonstrated that ER stress in chondrocytes is present in human osteoarthritis (OA), its role in the pathology of cartilage degeneration, such as chondrocyte apoptosis, remains unclear. In the present study, we investigated the expression of phosphorylated PERK (pPERK), ubiquitin (Ub), GRP78, CHOP, phosphorylated JNK (pJNK) and cleaved caspase-3 (C-CASP3) and the mRNA splicing of XBP1 (XBP1 splicing) in human OA cartilage by immunohistochemistry and RT-PCR. Additionally, human chondrocytes were treated with several concentrations of tunicamycin, an ER stress inducer, to assess the impact of ER stress on the mRNA expression of CHOP, XBP1 splicing and apoptosis, as determined by real-time PCR, RT-PCR and ELISA analyses respectively. In human OA cartilage, the number of chondrocytes expressing pPERK, Ub, CHOP and pJNK positively correlated with cartilage degeneration and the number of C-CASP3-positive chondrocytes. XBP1 splicing and GRP78 expression in severe OA containing the greatest number of C-CASP3-positive chondrocytes were similar to the levels in mild OA, however, XBP1 splicing was higher in moderate OA than in mild and severe OA. Tunicamycin dose dependently increased CHOP expression and apoptosis of cultured chondrocytes. Although tunicamycin upregulated XBP1 splicing in cultured chondrocytes, its impact on XBP1 splicing was weakened at higher concentrations. In conclusion, the present results indicate that ER stress may contribute to chondrocyte apoptosis along with OA progression, which was closely associated with an enhanced apoptotic response and a reduced protective response by the cells.

Tracing the first waves of lymphopoiesis in mice

RAG1/GFP knock-in mice were used to precisely chart the emergence and expansion of cells that give rise to the immune system. Lymphopoietic cells detectable in stromal co-cultures arose as early as E8.5, i.e. prior to establishment of the circulation within the paraaortic splanchnopleura (P-Sp). These cells were Tie2+ RAG1- CD34Lo/-Kit+ CD41-. While yolk sac (YS) also contained lymphopoietic cells after E9.5, CD41+ YS cells from ⩽25-somite embryos produced myelo-erythroid cells but no lymphocytes. Notch receptor signaling directed P-Sp cells to T lymphocytes but did not confer lymphopoietic potential on YS cells. Thus, definitive hematopoiesis arises in at least two independent sites that differ in lymphopoietic potential. Expression of RAG1, the earliest known lymphoid event, first occurred around E10.5 within the embryos. RAG1/GFP+ cells appeared in the liver at E11.0 and progenitors with B and/or T lineage potential were enumerated at subsequent developmental stages.

Up-regulated expression of cartilage intermediate-layer protein and ANK in articular hyaline cartilage from patients with calcium pyrophosphate dihydrate crystal deposition disease

OBJECTIVE

Excess accumulation of extracellular inorganic pyrophosphate (ePPi) in aged human cartilage is crucial in calcium pyrophosphate dihydrate (CPPD) crystal formation in cartilage matrix. Two sources of ePPi are ePPi-generating ectoenzymes (NTPPPH) and extracellular transport of intracellular PPi by ANK. This study was undertaken to evaluate the role of NTPPPH and ANK in ePPi elaboration, by investigating expression of NTPPPH enzymes (cartilage intermediate-layer protein [CILP] and plasma cell membrane glycoprotein 1 [PC-1]) and ANK in human chondrocytes from osteoarthritic (OA) articular cartilage containing CPPD crystals and without crystals.

METHODS

Chondrocytes were harvested from knee cartilage at the time of arthroplasty (OA with CPPD crystals [CPPD], n = 8; OA without crystals [OA], n = 10). Normal adult human chondrocytes (n = 1) were used as a control. Chondrocytes were cultured with transforming growth factor beta1 (TGFbeta1), which stimulates ePPi elaboration, and/or insulin-like growth factor 1 (IGF-1), which inhibits ePPi elaboration. NTPPPH and ePPi were measured in the media at 48 hours. Media CILP, PC-1, and ANK were determined by dot-immunoblot analysis. Chondrocyte messenger RNA (mRNA) was extracted for reverse transcriptase-polymerase chain reaction to study expression of mRNA for CILP, PC-1, and ANK. NTPPPH and ANK mRNA and protein were also studied in fresh frozen cartilage.

RESULTS

Basal ePPi elaboration and NTPPPH activity in conditioned media from CPPD chondrocytes were elevated compared with normal chondrocytes, and tended to be higher compared with OA chondrocytes. Basal expression of mRNA for CILP (chondrocytes) and ANK (cartilage) was higher in both CPPD chondrocytes and CPPD cartilage extract than in OA or normal samples. PC-1 mRNA was less abundant in CPPD chondrocytes and cartilage extract than in OA chondrocytes and extract, although the difference was not significant. CILP, PC-1, and ANK protein levels were similar in CPPD, OA, and normal chondrocytes or cartilage extracts. Both CILP and ANK mRNA expression and ePPi elaboration were stimulated by TGFbeta1 and inhibited by IGF-1 in chondrocytes from all sources.

CONCLUSION

CILP and ANK mRNA expression correlates with chondrocyte ePPi accumulation around CPPD and OA chondrocytes, and all respond similarly to growth factor stimulation. These findings suggest that up-regulated CILP and ANK expression contributes to higher ePPi accumulation from CPPD crystal-forming cartilage.

Reconstruction of large rotator-cuff tears with acellular dermal matrix grafts in rats

HYPOTHESIS

With the acellular dermal matrix (ADM), it may be possible to bridge large rotator cuff tears and induce tendon regeneration.

MATERIALS AND METHODS

A 3 x 5 mm defect of the rotator cuff was created on both shoulders of adult male Sprague-Dawley rats. The graft group (n = 15) underwent reconstruction of the rotator cuff defect with an ADM patch graft; in the defect group (n = 15) no repair was performed. We sacrificed 5 rats from each group at 2, 6, and 12 weeks after surgery and harvested both shoulders; 3 specimens were subjected to histological analysis and the other 7 specimens were used for biomechanical testing. The controls were 5 unoperated rats; they were sacrificed to obtain 3 histologic and 7 biomechanical control shoulder specimens.

RESULTS

At each time points, the graft group had significantly higher modified tendon maturing scores than the defect group (p < 0.002); specimens from the graft group demonstrated a greater mean ultimate force to failure than those from the defect group (p < 0.05). Within 12 weeks, the ADM graft was histologically incorporated into a structure resembling control specimen; the mean ultimate force to failure in control was significantly greater than in specimens from both groups (p < 0.01).

DISCUSSION

Although the defect was restored in the defect group, histologically and biomechanically specimens from the defect group were inferior to the graft group.

CONCLUSION

ADM grafts were useful as a scaffold in the reconstruction of large rotator cuff defects in rats.

LEVEL OF EVIDENCE

Basic science study.

Unique Properties of Fetal Lymphoid Progenitors Identified According to RAG1 Gene Expression

RAG1/GFP knockin mice were exploited to isolate and characterize fetal lymphoid progenitors. CD11b and IL-7Ralpha are expressed in a developmental stage-dependent fashion, revealing how substantial numbers of early lymphoid progenitors were discarded or neglected in previous studies. The myeloerythroid potential of fetal progenitors in clonal assays declined in synchrony with activation of the RAG1 locus but was not completely extinguished. Lymphoid differentiation corresponded to patterns of gene expression previously found for adult marrow, but no fraction of fetal liver was enriched with respect to B + T progenitors. Also, unlike adults, fetal lymphoid progenitors transiently expressed endothelial cell markers. These findings help to reconcile discrepancies in previous reports and suggest that the fetal immune system arises via unique mechanisms.

Construction of hybrid biphenyl (bph) and toluene (tod) genes for functional analysis of aromatic ring dioxygenases

Multicomponent enzyme complexes of biphenyl (BP) dioxygenase (Dox) encoded by the gene cluster, bphA1A2A3A4 in Pseudomonas pseudoalcaligenes strain KF707 [Taira et al., J. Biol. Chem. 267 (1992) 4844-4858] and toluene Dox encoded by the gene cluster, todC1C2BA in P. putida strain F1 [Zylstra et al., J. Biol. Chem. 264 (1989) 14940-14946], show high homologies (approx. 60%) for the corresponding subunit component in spite of the fact that they have discrete substrate specificities. We constructed hybrid gene clusters by replacing the gene component(s) between the large and small subunits of terminal Dox in the bph and tod gene clusters, and analyzed the function of a novel hybrid aromatic ring Dox. Escherichia coli cells expressing the hybrid gene clusters, todC1::bphA2A3A4, todC1C2::bphA3A4 and bphA1::todC2::bphA3A4, gained the ability to convert benzene-toluene and their derivatives to the dihydrodiols, indicating that the hybrid terminal Dox composed of TodC1::BphA2 and BphA1::TodC2 forms a functionally active multicomponent Dox associated with ferredoxin (Fer) (BphA3) and Fer reductase (BphA4). Moreover, hybrid Dox (composed of TodC1::BphA2A3A4 and TodC1C2::BphA3A4) showed a wide substrate specificity rather similar to that of the wild-type toluene Dox (TodC1C2BA). On the other hand, the hybrid Dox (BphA1::TodC2::BphA3A4) showed oxidative activities for the same compounds, but the rate of oxidation was dependent upon the substrate. These results suggest that (i) the two subunits of terminal Dox are critically involved in the substrate specificity for BP, benzene and their derivatives, and (ii) the electron transport proteins, Fer and Fer reductase, are exchangeable with one another between the BP Dox and toluene Dox complexes.

Arthroscopic repair of traumatic combined rotator cuff tears involving the subscapularis tendon

BACKGROUND

Although the use of arthroscopic repair to treat rotator cuff tears involving the subscapularis has increased, there are few studies on treatment outcomes and repair integrity. We hypothesized that arthroscopic repair of combined rotator cuff tears that include the subscapularis yields successful functional and structural outcomes.

METHODS

Our study population consisted of seventeen men and three women (twenty shoulders) whose mean age was 61.7 years. The mean duration of follow-up was 36.1 months, and all patients were followed for at least two years. All had traumatic full-thickness tears of the subscapularis and supraspinatus, and seven had a concomitant infraspinatus tear. The mean time from the injury to the surgery was 2.7 months. An arthroscopic suture-anchor technique was used for the repair. The shoulders were evaluated before and after the procedure with use of the University of California at Los Angeles (UCLA) score, the Japanese Orthopaedic Association (JOA) score, plain radiographs, and magnetic resonance imaging scans.

RESULTS

After arthroscopic repair, the mean UCLA and JOA scores significantly improved from 14.9 and 55.7 points to 31.1 and 91.0 points, respectively (p < 0.0001). According to the JOA rating scale, the outcome was excellent for thirteen patients (65%), good for five (25%), fair for one (5%), and poor for one (5%). Of the twenty patients, seven (35%) had recurrent tears after the surgery; four of them had originally had a three-tendon tear and the other three had had a two-tendon tear. Of these seven patients, one had an excellent outcome; five, a good outcome; and one, a fair outcome. The postoperative mean JOA score was significantly lower for the patients with a failed repair than it was for those with an intact repair (p = 0.0034). The patients with a failed repair also had a significantly higher mean age (68.4 years compared with 58.1 years for those with an intact repair; p = 0.014), and the prevalence of recurrent tears was significantly higher in the patients with severe tendon retraction compared with those with minimal or moderate tendon retraction (p = 0.0191).

CONCLUSIONS

Arthroscopic repair with use of the suture anchor technique is a safe and effective procedure for the treatment of combined rotator cuff tears involving the subscapularis tendon; it can alleviate shoulder pain and improve function and the range of motion. The postoperative integrity of the repair correlates with the clinical results. Patient age and the degree of tendon retraction can affect the integrity of the repair.

The effects of fibroblast growth factor-2 on rotator cuff reconstruction with acellular dermal matrix grafts

PURPOSE

Our purpose was to determine whether the local application of fibroblast growth factor (FGF) 2 accelerates regeneration and remodeling of rotator cuff tendon defects reconstructed with acellular dermal matrix (ADM) grafts in rats.

METHODS

Thirty adult male Sprague-Dawley rats were divided into equal groups undergoing FGF-treated and FGF-untreated repairs. All rats underwent placement of an ADM graft for the supraspinatus defect (3 x 5 mm). FGF-2 (100 microg/kg) in a fibrin sealant was applied to both shoulders in the FGF-treated group, whereas only fibrin sealant was applied in untreated group. At 2, 6, and 12 weeks after surgery, 5 rats (10 shoulders) in each group were sacrificed for histologic analysis (3 shoulders) and biomechanical testing (7 shoulders). The controls were 5 unoperated rats (3 histologic and 7 biomechanical control specimens).

RESULTS

Unoperated control tendons inserted into the bone by direct insertion; there was a zone of fibrocartilage between the tendon and bone. At 2 weeks, the FGF-treated group had tendon maturing scores similar to those in the untreated group (P > .05). At 6 and 12 weeks, the FGF-treated group had significantly higher scores (P < .05). At 2 weeks, specimens in both the treated and untreated groups exhibited similar strength; the ultimate tensile failure load was 6.0 +/- 4.0 N and 5.8 +/- 2.0 N, respectively (P > .05). At 6 weeks, the FGF-treated specimens were stronger, with an ultimate tensile failure load of 10.2 +/- 3.1 N compared with 7.2 +/- 2.2 N in the untreated group (P = .02). At 12 weeks, the FGF-treated specimens were stronger, with an ultimate tensile failure load of 15.9 +/- 1.6 N compared with 13.2 +/- 2.0 N in the untreated group (P = .0072), and there were no significant differences in strength compared with the controls (17.8 +/- 2.6 N) (P > .05).

CONCLUSIONS

The remodeling of ADM grafts placed in rat rotator cuff tendon defects was accelerated by the local administration of FGF-2.

CLINICAL RELEVANCE

The application of FGF-2 may result in improved histologic characteristics and biomechanical strength in ADM graft constructs in humans.