Combination of intramuscular transplantation of autologous mononuclear bone marrow cells with sympathectomy (L2, 3) in patients with peripheral arterial disease(PAD).

BACKGROUND: In most patients with severe, chronic extremity ischemic diseases, intervention or surgical treatment is often not suitable. Combination of intramuscular transplantation of autologous monocular bone marrow cells (AMBMCs) and sympathectomy (L2, 3) has been proved therapeutically beneficial. METHODS: We studied 170 patients (combined group 80, control group 90) with extremity ischemia (TAO, ASO FontaineⅡ,Ⅲ, Ⅳ) between January 2013 and September 2019. RESULTS: In contrast to pre-operation, the walking distance of patients increased significantly (from 61.34 ± 52.23 m to 156.0 ± 32.4 m, p < 0.01), and the ankle-brachial index (ABI) remarkably improved (from 0.28 ± 0.13 to 0.59 ± 0.23, p < 0.05). CONCLUSION: Combined therapy is feasible and effective for patients with peripheral arterial disease (PAD).

Activin A forms a non-signaling complex with ACVR1 and type II Activin/BMP receptors via its finger 2 tip loop.

Activin A functions in BMP signaling in two ways: it either engages ACVR1B to activate Smad2/3 signaling or binds ACVR1 to form a non-signaling complex (NSC). Although the former property has been studied extensively, the roles of the NSC remain unexplored. The genetic disorder fibrodysplasia ossificans progressiva (FOP) provides a unique window into ACVR1/Activin A signaling because in that disease Activin can either signal through FOP-mutant ACVR1 or form NSCs with wild-type ACVR1. To explore the role of the NSC, we generated 'agonist-only' Activin A muteins that activate ACVR1B but cannot form the NSC with ACVR1. Using one of these muteins, we demonstrate that failure to form the NSC in FOP results in more severe disease pathology. These results provide the first evidence for a biological role for the NSC in vivo and pave the way for further exploration of the NSC's physiological role in corresponding knock-in mice.

The role of pyrophosphate/phosphate homeostasis in terminal differentiation and apoptosis of growth plate chondrocytes.

Extracellular inorganic phosphate (P(i)) concentrations are the highest in the growth plate just before the onset of mineralization. The study reported here demonstrates that P(i) not only is required for hydroxyapatite mineral formation but also modulates terminal differentiation and apoptosis of growth plate chondrocytes. Extracellular P(i) stimulated terminal differentiation marker gene expression, including the progressive ankylosis gene (ank), alkaline phosphatase (APase), matrix metalloproteinase-13 (MMP-13), osteocalcin, and runx2, mineralization, and apoptosis of growth plate chondrocytes. The stimulatory effect of extracellular P(i) on terminal differentiation and apoptosis events of growth plate chondrocytes was dependent on the concentration, the expression levels of type III Na(+)/P(i) cotransporters, and ultimately P(i) uptake. A high extracellular P(i) concentration was required for the stimulation of apoptosis, whereas lower P(i) concentrations were required for the most effective stimulation of terminal differentiation events, including terminal differentiation marker gene expression and mineralization. Suppression of Pit-1 was sufficient to inhibit the stimulatory effects of extracellular P(i) on terminal differentiation events. On the other hand, increasing the local extracellular P(i) concentration by overexpressing ANK, a protein transporting intracellular PP(i) to the extracellular milieu where it is hydrolyzed to P(i) in the presence of APase, resulted in marked increases of hypertrophic and early terminal differentiation marker mRNA levels, including APase, runx2 and type X collagen, and slight increase of MMP-13 mRNA levels, but decreased osteocalcin mRNA level, a late terminal differentiation markers. In the presence of levamisole, a specific APase inhibitor to prevent hydrolysis of extracellular PP(i) to P(i), ANK overexpression of growth plate chondrocytes resulted in decreased mRNA levels of hypertrophic and terminal differentiation markers but increased MMP-13 mRNA levels. In conclusion, with extracellular PP(i) inhibiting and extracellular P(i) stimulating hypertrophic and terminal differentiation events, a precise regulation of PP(i)/P(i) homeostasis is required for the spatial and temporal control of terminal differentiation events of growth plate chondrocytes.

Progressive ankylosis protein (ANK) in osteoblasts and osteoclasts controls bone formation and bone remodeling.

The progressive ankylosis gene (ank) encodes a transmembrane protein that transports intracellular inorganic pyrophosphate (PP(i)) to the extracellular milieu. ank/ank mice, which express a truncated nonfunctional ANK, showed a markedly reduced bone mass, bone-formation rate, and number of tartrate-resistant acid phosphatase-positive (TRAP(+)) multinucleated osteoclasts. ANK function deficiency suppressed osteoblastic differentiation of ank/ank bone marrow stromal cells, as indicated by the decrease in the expression of bone marker genes, including osterix, reduced alkaline phosphatase activity, and mineralization. Runx2 gene expression levels were not altered. Conversely, overexpression of ANK in the preosteoblastic cell line MC3T3-E1 resulted in increased expression of bone marker genes, including osterix. Whereas runx2 expression was not altered in ANK-overexpressing MC3T3-E1 cells, runx2 transcriptional activity was increased. Extracellular PP(i) or P(i) stimulated osteoblastogenic differentiation of MC3T3-E1 cells or partially rescued delayed osteoblastogenic differentiation of ank/ank bone marrow stromal cells. A loss of PP(i) transport function ANK mutation also stimulated osteoblastogenic differentiation of MC3T3-E1 cells. Furthermore, ANK function deficiency suppressed the formation of multinucleated osteoclasts from ank/ank bone marrow cells cultured in the presence of macrophage colony-stimulating factor and receptor activator of nuclear factor-kappaB ligand. In conclusion, ANK is a positive regulator of osteoblastic and osteoclastic differentiation events toward a mature osteoblastic and osteoclastic phenotype.

Progressive ankylosis gene (ank) regulates osteoblast differentiation.

The progressive ankylosis gene (ank) is a transmembrane protein that transports intracellular pyrophosphate to the extracellular milieu. Human mutations of ank lead to craniometaphyseal dysplasia, a disease which is characterized by the overgrowth of craniofacial bones and osteopenia in long bones, suggesting that ANK plays a regulatory role in osteoblast differentiation. To determine the role of ANK in osteoblast differentiation, we suppressed ANK expression in the osteoblastic MC3T3-E1 cell line using siRNA and determined the expression of osteoblastic marker genes and the transcription factors osterix and runx2. In addition, we determined the osteoblastic differentiation of bone marrow stromal cells isolated from the bone marrow of ank/ank mice, which express a truncated, nonfunctional ANK protein, or wild-type littermates. Suppression of ANK expression in MC3T3-E1 cells led to a decrease in bone marker gene expression, including alkaline phosphatase, bone sialoprotein, osteocalcin and type I collagen. In addition, osterix gene expression was decreased in ANK expression-suppressed MC3T3 cells, whereas runx2 expression was increased. Bone marrow stromal cells isolated from ank/ank mice cultured in the presence of ascorbate-2-phosphate for up to 35 days showed markedly reduced mineralization compared to the mineralization of bone marrow stromal cells isolated from wild-type littermates. In conclusion, these findings suggest that ANK is a positive regulator of differentiation events towards a mature osteoblastic phenotype.

Collagen/annexin V interactions regulate chondrocyte mineralization.

Physiological mineralization in growth plate cartilage is highly regulated and restricted to terminally differentiated chondrocytes. Because mineralization occurs in the extracellular matrix, we asked whether major extracellular matrix components (collagens) of growth plate cartilage are directly involved in regulating the mineralization process. Our findings show that types II and X collagen interacted with cell surface-expressed annexin V. These interactions led to a stimulation of annexin V-mediated Ca(2+) influx resulting in an increased intracellular Ca(2+) concentration, [Ca(2+)](i), and ultimately increased alkaline phosphatase activity and mineralization of growth plate chondrocytes. Consequently, stimulation of these interactions (ascorbate to stimulate collagen synthesis, culturing cells on type II collagen-coated dishes, or overexpression of full-length annexin V) resulted in increase of [Ca(2+)](i), alkaline phosphatase activity, and mineralization of growth plate chondrocytes, whereas inhibition of these interactions (3,4-dehydro-l-proline to inhibit collagen secretion, K-201, a specific annexin channel blocker, overexpression of N terminus-deleted mutant annexin V that does not bind to type II collagen and shows reduced Ca(2+) channel activities) decreased [Ca(2+)](i), alkaline phosphatase activity, and mineralization. In conclusion, the interactions between collagen and annexin V regulate mineralization of growth plate cartilage. Because annexin V is up-regulated during pathological mineralization events of articular cartilage, it is possible that these interactions also regulate pathological mineralization.

Hyaluronan inhibits osteoclast differentiation via Toll-like receptor 4.

The differentiation of osteoclasts, cells specialized for bone resorption, is governed by two key factors, macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappaB ligand (RANKL). The extracellular matrix (ECM) is an important factor influencing cell fate. To date, little investigation on the relationship between ECM components and osteoclast differentiation has been documented. In this study, we uncovered a potent anti-osteoclastogenic effect of hyaluronan (HA), an ECM component present in bone marrow and soft connective tissues, in primary mouse and human osteoclast precursor cell cultures. The anti-osteoclastogenic function of HA was dependent on Toll-like receptor 4 (TLR4) but not on CD44. HA inhibited M-CSF-dependent signaling pathways involving Rac, reactive oxygen species and mitogen-activated protein kinases, resulting in suppression of transcription factors AP-1 and MITF that control RANK expression. Furthermore, in an in vivo mouse model of calvarial bone resorption assays HA reduced RANKL-induced bone erosion and osteoclastogenesis. Our results clearly show that HA inhibits osteoclast differentiation through TLR4 by interfering with M-CSF signaling, and point that the interaction between ECM components and innate immune receptors can play an important role in the regulation of bone metabolism.

Antioxidant alpha-lipoic acid inhibits osteoclast differentiation by reducing nuclear factor-kappaB DNA binding and prevents in vivo bone resorption induced by receptor activator of nuclear factor-kappaB ligand and tumor necrosis factor-alpha.

The relationship between oxidative stress and bone mineral density or osteoporosis has recently been reported. As bone loss occurring in osteoporosis and inflammatory diseases is primarily due to increases in osteoclast number, reactive oxygen species (ROS) may be relevant to osteoclast differentiation, which requires receptor activator of nuclear factor-kappaB ligand (RANKL). Tumor necrosis factor-alpha (TNF-alpha) frequently present in inflammatory conditions has a profound synergy with RANKL in osteoclastogenesis. In this study, we investigated the effects of alpha-lipoic acid (alpha-LA), a strong antioxidant clinically used for some time, on osteoclast differentiation and bone resorption. At concentrations showing no growth inhibition, alpha-LA potently suppressed osteoclastogenesis from bone marrow-derived precursor cells driven either by a high-dose RANKL alone or by a low-dose RANKL plus TNF-alpha (RANKL/TNF-alpha). alpha-LA abolished ROS elevation by RANKL or RANKL/TNF-alpha and inhibited NF-kappaB activation in osteoclast precursor cells. Specifically, alpha-LA reduced DNA binding of NF-kappaB but did not inhibit IKK activation. Furthermore, alpha-LA greatly suppressed in vivo bone loss induced by RANKL or TNF-alpha in a calvarial remodeling model. Therefore, our data provide evidence that ROS plays an important role in osteoclast differentiation through NF-kappaB regulation and the antioxidant alpha-lipoic acid has a therapeutic potential for bone erosive diseases.