Tibial Periosteum Research Articles

Elevation and distraction of the Tibial periosteum in the management of chronic ischemic lower limb diseases.

This study investigates the effectiveness of tibia periosteum distraction (TPD) applied to the tibial periosteum, an innovative approach grounded in Ilizarov's tension-stress theory, for the treatment of ischemic diabetic foot and vasculitic foot conditions. A retrospective analysis was conducted on 33 patients (36 limbs) who underwent TPD between June 2019 and May 2022. The study comprised 21 males (23 limbs) and 12 females (13 limbs), aged 41 to 80 years (mean age: 63.4 years). Diabetic foot accounted for 27 cases, thromboangiitis obliterans for 2 cases, and arterial occlusive disease for 4 cases. The distribution of affected limbs included 15 left feet and 21 right feet. Periosteum traction commenced on the third postoperative day at a rate of approximately 0.75mm/day, adjusted biweekly. The traction device was removed after two weeks. Evaluation included capillary refill and wound healing assessment, along with pre- and postoperative analysis of foot skin temperature, ankle-brachial index (ABI), visual analogue scale (VAS) pain scores, and peripheral blood oxygen saturation. CT angiography (CTA) was utilized to assess vascular conditions in both lower limbs. All 33 patients were successfully followed up for a duration ranging from 4 to 24 weeks (mean: 11.03 weeks). VAS pain scores significantly decreased from preoperative (5.09 ± 1.70, range: 2-8) to postoperative two weeks (2.24 ± 0.90, range: 1-4) (t = 9.44, p < .001). Oxygen saturation levels increased from 83.88% ± 11.82% (range: 58%-97%) preoperatively to 91.36% ± 5.69% (range: 76%-98%) at two weeks postoperatively (t = -4.21, p < .001). Foot skin temperature also showed a significant increase (t = -3.98, p < .001). Capillary refill test at two weeks postoperatively demonstrated notable improvement. CTA revealed evident neovascularization in the operated limbs compared to preoperative conditions. Wound improvement was significant in all 33 patients within two months postoperatively. TPD emerges as a promising technique for chronic ischemic lower limb diseases, demonstrating favorable preliminary outcomes in wound healing promotion and amputation rate reduction. Nevertheless, large-scale randomized controlled trials are essential to further validate its efficacy.

Vitamin A enhanced periosteal osteoclastogenesis is associated with increased number of tissue-derived macrophages/osteoclast progenitors

A deleterious effect of elevated levels of vitamin A on bone health has been reported in numerous clinical studies. Mechanistic studies in rodents have shown that numbers of periosteal osteoclasts are increased, while endocortical osteoclasts are simultaneously decreased by vitamin A treatment. These observations indicate that osteoclastogenesis on the endocortical and periosteal surfaces of bone is differentially controlled by vitamin A. The present study investigated the in vitro and in vivo effect of all-trans retinoic acid (ATRA), the active metabolite of vitamin A, on periosteal osteoclast progenitors. Mouse calvarial bone cells were cultured in media containing ATRA, with or without the osteoclastogenic cytokine RANKL, on plastic dishes or bone discs. Whereas ATRA did not stimulate osteoclast formation alone, the compound robustly potentiated the formation of RANKL-induced bone resorbing osteoclasts. This effect was due to stimulation by ATRA (EC50 ∼3nM) on the numbers of macrophages/osteoclast progenitors in the bone cell cultures, as assessed by mRNA and protein expression of several macrophage and osteoclast progenitor cell markers, such as M-CSF receptor, RANK, F4/80 and CD11b, as well as by FACS-analysis of CD11b+/F480+/Gr1- cells. The stimulation of macrophage numbers in the periosteal cell cultures was not mediated by increased M-CSF or IL-34. In contrast, ATRA did not enhance macrophages in bone marrow cell cultures. Importantly, ATRA treatment upregulated the mRNA expression of several macrophage-related genes also in the periosteum of tibia in adult mice. These observations demonstrate a novel mechanism by which vitamin A enhances osteoclast formation specifically on periosteal surfaces.

Repair of posterior laryngeal cleft: a 10-year experience in a tertiary referral hospital.

This study aimed to present experience with surgical treatment of laryngeal cleft cases through both open and endoscopic approaches. A retrospective evaluation of all patients diagnosed as having a laryngeal cleft in a tertiary hospital over 10 years was performed. Pre-operative data, conservative and surgical management of cases, and outcomes were collected, tabulated and analysed. This study included 43 patients aged from 2 to 44 months with a median of 9.19 months. Concerning management technique, 12 patients had conservative treatment and the remaining 31 underwent a surgical procedure (of them, 20 patients underwent endoscopic intervention and 11 had the open surgical technique). In the open group, we used either tibial periosteum (six cases) or harvested costal cartilage (five cases). Surgical management in the form of endoscopic Coblation-assisted or an open approach is indicated in severe cases or mild cases not responding to conservative management.

Techniques in Pediatric Anterior Cruciate Ligament Reconstruction

In recent years, the frequency of anterior cruciate ligament (ACL) tears and ACL reconstruction (ACLR) in skeletally immature patients has increased. Because distal femoral and proximal tibial physes account for the majority of lower-extremity growth, surgical technique and graft selection are crucial to minimize iatrogenic physeal injury. Combined extra- and intra-articular, all-epiphyseal, and transphyseal with soft-tissue grafts are the most common ACLR techniques used in children. Combined extra- and intra-articular ACLR typically is offered to prepubescent patients with ≥2 years of growth remaining. This technique uses iliotibial band (ITB) autograft passed over the lateral femoral condyle and fixed to the anterior tibial periosteum. All-epiphyseal ACLR is similarly used in patients with ≥2 years of growth remaining, provided sufficient epiphyseal maturity to accommodate an all-epiphyseal socket because both the femoral and tibial tunnels are contained within the epiphyses. In postpubertal patients with <2 years of growth remaining, transphyseal ACLR using a soft-tissue autograft (typically hamstring or quadriceps tendon) and metaphyseal femoral fixation can be performed. This minimizes risk of physeal injury. In borderline patients with approximately 2 years of growth remaining, an additional option includes partial transphyseal ACLR, which uses a soft-tissue graft and a transphyseal tibial tunnel, but an all-epiphyseal or over-the-top femoral graft trajectory. Recently, transphyseal ITB ACLR and hybrid transphyseal hamstring with combined over-the-top ITB ACLR also have been described. Existing clinical studies focused on pediatric and adolescent ACL reconstructions have reported a wide range of graft rupture rates for these techniques (4.3%-25%), with contralateral ACL injury rates of 2.9% to 15.6%. Ongoing multicenter research is underway to directly compare surgical techniques for this demographic and quantify graft rupture rates and other clinical outcomes.

New insights into pathogenesis of congenital pseudarthrosis of tibia in children using periosteum proteomics analysis.

The exact etiology and pathogenesis of congenital pseudarthrosis of tibia (CPT) are not clear. Quantitative proteomics analysis plays a vital role in disease pathology research. Tandem mass tag (TMT)-based proteomics techniques were employed to identify and analyze the differentially expressed proteins (DEP) in the tibia periosteum tissues of CPT patients. The samples were divided into three groups: CPT with NF1 group, CPT without NF1 group (non-NF1-CPT), and control group (patients with open tibial fracture). A fold change ≥1.5 or ≤0.66 and P-value <0.05 were used as the thresholds to screen DEPs. Subsequently, bioinformatics resources such as online tools DAVID and String were used to generate gene ontology (GO) annotation, KEGG pathways enrichment, and protein-protein interaction (PPI) network for these DEPs. The results show that a total of 347 proteins were differentially expressed in NF1-CPT groups, 212 of which were upregulated and 135 were downregulated. There were more DEPs in non-NF1-CPT groups; we identified 467 DEPs, including 281 upregulated and 186 downregulated. Among them, NF1-CPT groups and non-NF1-CPT groups shared 231 DEPs, and the remaining 230 DEPs showed the same expression trend in the two disease groups, with 117 upregulated and 113 downregulated. In particular, 116 proteins were altered only in NF1-CPT groups (94 were upregulated and 22 were downregulated), whereas 236 proteins were altered only in non-NF1-CPT groups (164 were upregulated and 72 were downregulated). Finally, compared with non-NF1-CPT groups, 47 proteins changed 1.5-fold and P-value < 0.05 in NF1-CPT groups. To sum up, we found that common DEPS in periosteum of NF1-CPT and non-NF1-CPT groups are mainly involved in cell matrix assembly, cell adhesion, AKT-PI3K signal pathway activation, and vascular agglutination, which indicate that these are the pathological characteristics of CPT. The osteogenic ability is weak, the osteoclastic ability is strong, the vascular lumen is narrow, the invasive growth and the proliferation of fibroblasts are enhanced in CPT patients.

Abstract 5974: Multimodal molecular imaging detects early reoxygenation induced by hyaluronan depletion in pancreatic cancer model mouse

Abstract [Purpose] In pancreatic ductal adenocarcinoma (PDAC) which is characterized by an intense desmoplastic feature, the extracellular matrix (ECM) can significantly influence the tumor microenvironment (TME). Hyaluronan (HA), a major component of ECM, is associated with elevated tumor pressure, vascular collapse, and poor perfusion in TME, conferring hypoxia. HA expression is also correlated with poor prognosis in the patients with PDAC. PEGylated human hyaluronidase (PEGPH20) enzymatically depletes hyaluronan in tumors. The resultant improvement in vascular patency and blood perfusion is expected to increase the delivery of therapeutic molecules. The aim of this study was to investigate the change in physiologic and metabolic profile of the tumor in response to treatment with PEGPH20 using multi-modal imaging techniques. We also investigated the capability of PEGPH20 to enhance treatment effect of radiation. [Methods] Athymic nude mice were inoculated with BxPC3 (human pancreatic adenocarcinoma) tumor cells transduced with hyaluronan synthase 3 (HAS3) to the right tibial periosteum. BxPC3-HAS3 tumor treated with PEGPH20 or control buffer were scanned with Electron paramagnetic Resonance imaging (EPRI), dynamic contrast enhanced (DCE) MRI, ultra-small superparamagnetic iron oxide (USPIO) MRI, Photoacoustic imaging (PAI), and Hyperpolarized 13C-MRI using [1-13C] pyruvate to evaluate intratumor pO2, intratumor perfusion, blood volume, O2 saturation, and glycolysis, respectively. [Results] EPRI showed significantly increased pO2 in PEGPH20 treated group. DCE-MRI and USPIO-MRI showed improved perfusion/permeability and local blood volume, respectively after PEGPH20 treatment, accounting for the increase in tumor oxygenation. PAI provided the evidence of immediate changes in tumor oxygenation after treatment. Hyperpolarized 13C-MRI using [1-13C] pyruvate suggested the decreased glycolytic flux evaluated by lactate/pyruvate ratio after PEGPH20 treatment. Combination of radiotherapy and PEGPH20 synergistically delayed tumor progression and prolonged the survival. [Conclusions] This study examined the effect of PEGPH20 on TME in PDAC xenograft model by using non-invasive multimodal imaging techniques. In summary, the non-invasive imaging modalities were useful in evaluating the changes in hemodynamics and metabolism in TME induced by modulation of ECM such as PEGPH20 treatment. PEGPH20 enhanced treatment effect of radiation therapy. The results validated the utility of the imaging methods to non-invasively monitor the changes in TME and predicted the radiosensitizing effect of hyaluronan depletion. Citation Format: Yu Saida, Tomohiro Seki, Shun Kishimoto, Jeffrey R. Brender, Gadisetti VR. Chandramouli, Yasunori Otowa, Kota Yamashita, Kazutoshi Yamamoto, Nallathamby Devasahayam, Murali C. Krishna. Multimodal molecular imaging detects early reoxygenation induced by hyaluronan depletion in pancreatic cancer model mouse [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5974.

Lower Leg Muscle Stiffness on Two-Dimensional Shear Wave Elastography in Subjects With Medial Tibial Stress Syndrome.

We aimed to explore, which muscle stiffness changes may be related to medial tibial stress syndrome (MTSS) and the correlation between the medial tibial periosteal thickness and lower leg muscle stiffness. This study included 63 subjects distributed into 3 groups: the symptomless group, the MTSS group, and the control group. The lower leg muscle stiffness of the tibialis anterior (TA), extensor digitorum longus (EDL), peroneus longus (PL), soleus (SOL), lateral gastrocnemius (LG), medial gastrocnemius (MG), tibialis posterior (TP), and flexor digitorum longus (FDL) in the 3 groups was obtained by two-dimensional shear wave elastography. Differences in the muscle stiffness and medial tibial periosteal thickness in the 3 groups were determined by one-way analysis of variance (ANOVA) and least significant difference tests. The relationships between the periosteal thickness and the muscle stiffness were assessed using Pearson correlations. The shear wave velocity (SWV) of all lower leg muscles except the EDL was higher in the symptomless and MTSS groups than in the control group (TA, P=.001; PL, P=.006; SOL, P < .001; LG, P < .001; MG, P < .001; TP, P < .001; FDL, P=.013; and ANOVA). A significant difference was found in the SWV of the SOL, TP, and FDL between the control and symptomless groups (P=.041, P < .001, and P=.013, respectively). Moreover, the medial tibial periosteum was thickened after running training, and its thickness was positively correlated with muscle stiffness. The medial tibia periosteal thickness is positively correlated with the lower leg muscles stiffness. Changes in SOL, TP, and FDL stiffness may be related to the occurrence of MTSS.

MRI findings of tibialis anterior friction syndrome: a mimic of tibial stress injury.

To describe a distinct constellation of MRI demonstrated soft tissue abnormalities centred around the tibialis anterior tendon in a subset of patients presenting as suspected tibial stress injury. A retrospective review was performed of the clinical and MRI imaging findings from 5 selected patients referred for MRI with suspected tibial stress injury. MRI studies at presentation of each case were systematically reviewed for peritendinous fluid, tibialis anterior tendon change, tibialis anterior muscle and myotendinous junction oedema, periosteal oedema over the tibia and tibial marrow oedema. All 5 cases were athletes (3 soccer players, 2 runners) of between 20 and 40years of age. On MRI, all 5 cases demonstrated peritendinous fluid around an intact tibialis anterior tendon. This fluid was maximal at the junction of mid and distal thirds of the lower leg, and extended down to the superior extensor retinaculum, with a mean cranio-caudal length of 13cm (range 8-17cm). Associated oedema was present in the surrounding subcutaneous tissue, tibial periosteum and distal tibialis anterior musculotendinous junction. Peritendinous fluid around an intact tibialis anterior tendon over the mid-to-distal third tibia, with surrounding subcutaneous, periosteal and tibialis anterior myotendinous junction oedema is demonstrable on MRI in a subset of patients presenting as suspected tibial stress injury. A friction syndrome of tibialis anterior between the superior extensor retinaculum and the anterior tibia is proposed as the aetiology of this entity.

Contribution of TRESK two-pore domain potassium channel to bone cancer-induced spontaneous pain and evoked cutaneous pain in rats.

Cancer-associated pain is debilitating. However, the mechanism underlying cancer-induced spontaneous pain and evoked pain remains unclear. Here, using behavioral tests with immunofluorescent staining, overexpression, and knockdown of TRESK methods, we found an extensive distribution of TRESK potassium channel on both CGRP+ and IB4+ nerve fibers in the hindpaw skin, on CGRP+ nerve fibers in the tibial periosteum which lacks IB4+ fibers innervation, and on CGRP+ and IB4+ dorsal root ganglion (DRG) neurons in rats. Moreover, we found a decreased expression of TRESK in the corresponding nerve fibers within the hindpaw skin, the tibial periosteum and the DRG neurons in bone cancer rats. Overexpression of TRESK in DRG neurons attenuated both cancer-induced spontaneous pain (partly reflect skeletal pain) and evoked pain (reflect cutaneous pain) in tumor-bearing rats, in which the relief of evoked pain is time delayed than spontaneous pain. In contrast, knockdown of TRESK in DRG neurons produced both spontaneous pain and evoked pain in naïve rats. These results suggested that the differential distribution and decreased expression of TRESK in the periosteum and skin, which is attributed to the lack of IB4+ fibers innervation within the periosteum of the tibia, probably contribute to the behavioral divergence of cancer-induced spontaneous pain and evoked pain in bone cancer rats. Thus, the assessment of spontaneous pain and evoked pain should be accomplished simultaneously when evaluating the effect of some novel analgesics in animal models. Also, this study provides solid evidence for the role of peripheral TRESK in both cancer-induced spontaneous pain and evoked cutaneous pain.

Antagonism Between PEDF and TGF-β Contributes to Type VI Osteogenesis Imperfecta Bone and Vascular Pathogenesis.

Osteogenesis imperfecta (OI) is a heterogeneous genetic disorder of bone and connective tissue, also known as brittle bone disease. Null mutations in SERPINF1, which encodes pigment epithelium-derived factor (PEDF), cause severe type VI OI, characterized by accumulation of unmineralized osteoid and a fish-scale pattern of bone lamellae. Although the potent anti-angiogenic activity of PEDF has been extensively studied, the disease mechanism of type VI OI is not well understood. Using Serpinf1(-/-) mice and primary osteoblasts, we demonstrate that loss of PEDF delays osteoblast maturation as well as extracellular matrix (ECM) mineralization. Barium sulfate perfusion reveals significantly increased vessel density in the tibial periosteum of Serpinf1(-/-) mouse compared with wild-type littermates. The increased bone vascularization in Serpinf1(-/-) mice correlated with increased number of CD31(+)/Endomucin(+) endothelial cells, which are involved in the coupling angiogenesis and osteogenesis. Global transcriptome analysis by RNA-Seq of Serpinf1(-/-) mouse osteoblasts reveals osteogenesis and angiogenesis as the biological processes most impacted by loss of PEDF. Intriguingly, TGF-β signaling is activated in type VI OI cells, and Serpinf1(-/-) osteoblasts are more sensitive to TGF-β stimulation than wild-type osteoblasts. TGF-β stimulation and PEDF deficiency showed additive effects on transcription suppression of osteogenic markers and stimulation of pro-angiogenic factors. Furthermore, PEDF attenuated TGF-β-induced expression of pro-angiogenic factors. These data suggest that functional antagonism between PEDF and TGF-β pathways controls osteogenesis and bone vascularization and is implicated in type VI OI pathogenesis. This antagonism may be exploited in developing therapeutics for type VI OI utilizing PEDF and TGF-β antibody. © 2022 American Society for Bone and Mineral Research (ASBMR). This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

The effect of bone inhibitors on periosteum-guided cartilage regeneration

The regeneration capacity of knee cartilage can be enhanced by applying periosteal grafts, but this effect varies depending on the different sources of the periosteal grafts applied for cartilage formation. Tibia periosteum can be used to enhance cartilage repair. However, long-term analysis has not been conducted. The endochondral ossification capacity of tibia periosteum during cartilage repair also needs to be investigated. In this study, both vascularized and non-vascularized tibia periosteum grafts were studied to understand the relationship between tissue perfusion of the periosteum graft and the effects on cartilage regeneration and bone formation. Furthermore, anti-ossification reagents were added to evaluate the efficacy of the prevention of bone formation along with cartilage regeneration. A critical-size cartilage defect (4 × 4 mm) was created and was covered with an autologous tibia vascularized periosteal flap or with a non-vascularized tibia periosteum patch on the knee in the rabbit model. A portion of the vascularized periosteum group was also treated with the anti-osteogenic reagents Fulvestrant and IL1β to inhibit unwanted bone formation. Our results indicated that the vascularized periosteum significantly enhanced cartilage regeneration in the cartilage defect region in long-term treatment compared to the non-vascularized group. Furthermore, the addition of anti-osteogenic reagents to the vascularized periosteum group suppressed bone formation but also reduced the cartilage regeneration rate. Our study using vascularized autologous tissue to repair cartilage defects of the knee may lead to the modification of current treatment in regard to osteoarthritis knee repair.

An Alternative Tibial Osteotomy Technique.

IntroductionThe anterior approach to a tibial osteotomy commonly employs a small incision and multiple drill holes followed by completion with an osteotome. Potential complications are damage to the anterior tibial periosteum and posterior neurovascular structures.Materials and MethodsWe describe an alternative method using two small incisions, which avoids elevation of the anterior tibial periosteum and directs the osteotome away from posterior neurovascular structures.ResultsThis technique has been successfully performed on 15 consecutive tibias, with no neurovascular complications or skin healing issues.ConclusionThis tibial osteotomy technique can be performed quickly and safely using a minimally invasive approach as an alternative to the traditional anterior approach.How to cite this articleIobst C. An Alternative Tibial Osteotomy Technique. Strategies Trauma Limb Reconstr 2020;15(1):47–49.

Anatomic Risk to the Neurovascular Structures With a Medially Based All-Inside Syndesmosis Suture Button Technique

Recent evidence suggests that the use of suture button devices for ankle syndesmosis fixation is increasing. Multiple studies have shown some concern about damaging the greater saphenous neurovasculature with placement of the anchor point on the medial tibial cortex. We hypothesized that an all-inside button deployment technique would allow for a low risk to medial soft tissue structures. A total of 40 syndesmosis suture buttons were placed into 10 separate cadaveric lower limbs, using the newly developed technique. Four suture buttons were sequentially placed from distal to proximal in each limb within the zone of typical syndesmosis fixation, using fluoroscopic guidance. A medial incision was then performed to evaluate the relationship of the suture buttons to the medial soft tissue structures and the medial malleolus. Thirteen of 40 suture buttons (32.5%) were placed anterior, 7 (17.5%) posterior, and 20 (50%) with a portion of the button directly deep to the saphenous vein. Two of 40 buttons (5%) were placed within the tibial periosteum, and 38 (95%) were subfascial and directly superficial to the periosteum. Four of 40 (10%) limbs revealed a perforation in the saphenous vein from the guidepin. In conclusion, risks to the medial neurovascular structures exist with the medial deployment technique, but they appear to be mitigated compared with previous publications. The necessity of a medial incision to evaluate for soft tissue entrapment may not be necessary in all patients, as this technique appears to be safe, accurate, and reproducible.

Identification of Functionally Distinct Mx1+αSMA+ Periosteal Skeletal Stem Cells.

The periosteum is critical for bone maintenance and healing. However, the invivo identity and specific regulatory mechanisms of adult periosteum-resident skeletal stem cells are unknown. Here, we report animal models that selectively and durably label postnatal Mx1+αSMA+ periosteal stem cells (P-SSCs) and establish that P-SSCs are a long-term repopulating, functionally distinct SSC subset responsible forlifelong generation of periosteal osteoblasts. P-SSCs rapidly migrate toward an injury site, supply osteoblasts and chondrocytes, and recover new periosteum. Notably, P-SSCs specifically express CCL5 receptors, CCR3 and CCR5. Real-time intravital imaging revealed that the treatment with CCL5 induces P-SSC migration invivo and bone healing, while CCL5/CCR5 deletion, CCR5 inhibition, or local P-SSC ablation reduces osteoblast number and delays bone healing. Human periosteal cells express CCR5 and undergo CCL5-mediated migration. Thus, the adult periosteum maintains genetically distinct SSC subsets with a CCL5-dependent migratory mechanism required for bone maintenance and injury repair.

Concentrated growth factor promotes proliferation, osteogenic differentiation, and angiogenic potential of rabbit periosteum-derived cells in vitro

ObjectiveThe aim of this research is to investigate the effects of concentrated growth factor (CGF) on the proliferation, osteogenic differentiation, and angiogenic potential of rabbit periosteum-derived cells (PDCs) in vitro.MethodsPDCs were isolated from the femoral and tibial periosteum of rabbits and cultured with or without CGF membranes or CGF conditioned media. Scanning electron microscopy (SEM) was used for the structural characterization. Cell Counting Kit-8 assay was used to measure cell proliferation. Alkaline phosphatase (ALP) activity of PDCs was also measured. Immunohistochemistry was used to detect the expression of CD34. Enzyme-linked immunosorbent assay (ELISA), quantitative real-time PCR (qPCR), and Western blot were used to evaluate the secretion and expression levels of osteogenic differentiation markers (bone morphogenetic protein-2, type I collagen, osteocalcin) and angiogenesis markers (vascular endothelial growth factor, basic fibroblast growth factor) in supernatants and PDCs at days 3, 7, 14, and 21.ResultsThe SEM analysis showed a dense three-dimensional fibrin network in CGF, and CGF membranes were covered by PDCs with elongated or polygonal morphological features. Compared with the control group, CGF significantly promoted the proliferation of PDCs during the experimental period (p < 0.05). Immunohistochemistry revealed that PDCs were dispersedly distributed among the CGF substrates, and CD34-positive cells were also present. Moreover, CGF significantly increased the ALP activity and upregulated the expression and secretion of osteogenic differentiation and angiogenesis markers in PDCs at days 3, 7, 14, and 21 (p < 0.05).ConclusionCGF can increase the proliferation and promote the osteogenic differentiation and angiogenic potential of PDCs in vitro. These results indicate that CGF can be used as a new therapeutic means for biotechnological and clinical applications.

Exercise-induced sympathetic dilatation in arterioles of the guinea pig tibial periosteum.

Strength training induces not only muscle growth but also increased bone strength, a change that is expected to be associated with increased bone blood flow. However, the effects of exercise on contractile properties of bone microvascultaure have not been investigated. Once-a-week strength training with electrical muscle stimulation was applied unilaterally to tibialis anterior muscle of guinea pigs, while muscle force was measured from both legs to compare their muscle strength and endurance. After 10 weeks of training, changes in the arteriolar diameters of isolated periosteum taken from both trained and non-trained legs were measured using a video tracking system. Electrical field stimulation evoked a phasic constriction followed by a sustained dilatation in periosteal arterioles of trained legs, while triggering only vasoconstriction in the arterioles of non-trained legs. In trained leg arterioles, phentolamine, an α-adrenoceptor antagonist, inhibited both the constriction and dilatation. Prazosin, an α1-adrenoceptor antagonist, inhibited only the constriction, while yohimbine, α2-adrenoceptor antagonist, or l-nitro arginine (L-NA), a nitric oxide (NO) synthase inhibitor, inhibited the dilatation. In non-trained leg arterioles, phentolamine or prazosin largely suppressed the constriction, but failed to unmask any dilatation. Consistently, noradrenaline (NAd)-induced arteriolar constriction was enhanced and prolonged by L-NA in trained but not non-trained side arterioles. Thus, NAd released from sympathetic nerves appears to activate endothelial α2-adrenoceptors to release NO resulting in the sustained dilatation of periosteum arterioles from trained leg. The altered sympathetic vasomotor function would facilitate the blood supply to the bone and may contribute to the exercise-induced bone strength gain.

Periosteal Osteogenic Capacity Depends on Tissue Source.

Periosteal osteogenic capacity can be exploited to enhance bone formation in the fields of tissue engineering and regenerative medicine. Despite this importance, there have been no studies examining the composition, structure, and osteogenic capacity of periostea from different bone sources. In this study, structure and osteogenic factor content were compared among periostea from rib, calvarial, femoral, and tibial bones, in which the native bones of these four regions were harvested and subjected to histological analysis. The osteogenic capacity of grafted periosteum was evaluated using an in vivo vascularized pedicle model of bone tissue engineering. Poly(ethylene glycol)-poly(l-lactic acid) (PEG-PLLA) copolymer hydrogels were seeded with bone marrow mesenchymal stem cells and implanted with grafted periosteum harvested from either calvarial or tibial bone, which were representative of thin and thick native periostea, respectively. The cambium layer thickness of periostea from the femoral and tibial bones (36.9% ± 2.5% and 36.8% ± 2.6%) was greater than that from the calvarial and rib bones (26.8% ± 2.4% and 25.5% ± 1.9%). The osteocalcin and alkaline phosphatase levels were comparatively higher in the femoral and tibial periostea than those in periostea harvested from the calvarial and rib bones. The construct implanted with grafted tibial periosteum resulted in greater neo-bone regeneration and higher osteocalcin and alkaline phosphatase expression. This study is the first investigation of the osteogenic capacity of periostea from diverse sources. The results can be used to guide clinical strategies that exploit periostea for tissue engineering and clinical applications.

PO-264 Preclinical studies with pegvorhyaluronidase alfa (PEGPH20) in combination with FOLFIRINOX (FFX) chemotherapy in models of pancreatic ductal adenocarcinoma

IntroductionHyaluronan (HA) accumulates in the tumour microenvironment (TME) of many solid tumours and has been associated with tumour progression and negative clinical outcomes. Pegvorhyaluronidase alfa (PEGPH20, P) is a novel biologic that enzymatically degrades HA. In preclinical models, P-mediated enzymatic degradation of HA is associated with decreased tumour interstitial fluid pressure, increased tumour perfusion, and increased access and anti-tumour efficacy of cytotoxic and immunotherapies. As pancreatic ductal adenocarcinoma (PDA) has been identified as a cancer type that accumulates high levels of HA, here we evaluated whether P alters the activity of the cytotoxic components of FOLFIRINOX (FFX), a common therapeutic regimen for advanced PDA, on human and murine PDA cells. We also evaluated p+FFX in vivo anti–tumour activity in BxPC3/HAS3, a HA accumulating human PDA model.Material and methodsFor in vitro experiments, fluorouracil, irinotecan and oxaliplatin were evaluated individually and in combination in both 2D culture and 3D tumour spheroids. For in-vivo evaluation, mice were inoculated with BxPC3/HAS3 cells adjacent to the right tibial periosteum and tumour growth was monitored via ultrasonography. When tumours reached ~230 mm3, mice (n=8/group) were staged into treatment groups: 1) vehicle; 2) 0.0375 mg/kg P BIW; 3) low FFX - 30 mg/kg leucovorin, 15 mg/kg fluorouracil, 30 mg/kg irinotecan, and 1.2 mg/kg oxaliplatin QW; 4) high FFX - 65 mg/kg leucovorin, 32.5 mg/kg fluorouracil, 65 mg/kg irinotecan, and 2.6 mg/kg oxaliplatin QW; 5) p+low FFX; and 6) p+high FFX. FFX was administered 24 hour after P.Results and discussionsPDA cells were more sensitive to chemotherapy treatment in 2D than 3D culture. The TME-modifying enzyme P did not show an effect on chemotherapy sensitivity, whether tested as individual or combined cytotoxics. In the BxPC3/HAS3 model, P increased the anti-tumour efficacy of low FFX 4-fold (56.3% vs. 11.3% tumour growth inhibition [TGI], respectively) and extended median survival time (MST) by >36% (32d vs. 23.5d, respectively), whereas P increased the efficacy of high FFX by 61% (64.3% vs. 39.8% TGI, respectively) and extended MST by 12.5% (36d vs. 32d, respectively). A maximum 5% BW loss was observed following the initial FFX dose.ConclusionTaken together, the results suggest that P does not affect the cytotoxic activity of FFX components on PDA cells in culture, and that P-mediated HA degradation improves the anti-tumour efficacy of FFX (especially suboptimal doses) in a preclinical PDA model.

PO-262 Remodelling of the tumour microenvironment by pegvorhyalurondiase alfa (PEGPH20): a novel, first-in-class biologic that enzymatically degrades tumour hyaluronan (HA) to improve anti-tumour efficacy

IntroductionHyaluronan (HA) is a naturally occurring glycosaminoglycan that can accumulate in the tumour microenvironment (TME). In pancreatic and other cancers, high levels of HA are associated with poor clinical outcome. In mouse models, high levels of HA in the TME can increase interstitial fluid pressure and compress tumour vasculature, thereby impairing delivery of anti-cancer therapeutics. Here, a novel, first-in-class biologic that enzymatically degrades HA, PEGPH20, increased tumour vascular volume (VV) and improved anti-tumour efficacy when combined with chemotherapy or checkpoint inhibitor antibodies in multiple HA-accumulating tumour models.Material and methodsVarious human and mouse cancer cell lines were transduced with hyaluronan synthase 3 (HAS3) to increase HA production, and implanted in the mammary fat pat (4 T1/HAS3) or adjacent to the tibial periosteum (all other cell lines). Tumour VV was measured by high resolution ultrasound coupled with micro-bubbles (A549/HAS3 and WT-CLS1/HAS3), or IHC (CT26/HAS3), following PEGPH20 treatment (0.0375 mg/kg or 1 mg/kg, IV, 2qw). For BxPC3/HAS3 studies, mice were dosed with vehicle or PEGPH20 (4.5 mg/kg, IV, 2qw)±nab paclitaxel (NAB, 10 mg/kg, IV, 2qw)±gemcitabine (GEM, 180 mg/kg, IP; 24 hour after PEGPH20 ±NAB, qw). For AsPC1/HAS3 studies, mice were dosed with vehicle or PEGPH20 (0.0375 mg/kg, IV, 2qw)±NAB (10 mg/kg, IV, qw)±GEM (180 mg/kg, IP; 24 hour after PEGPH20 ±NAB, qw). For checkpoint inhibitor studies (CT26/HAS3, 4 T1/HAS3, Pan02/HAS3), mice were dosed with PEGPH20 (0.0375 mg/kg, IV) 24 hour prior to anti-CTLA4 (clone 9D9, 4 mg/kg, IP) or anti-PD-L1 (clone 10F.9G2, 5 mg/kg, IP).Results and discussionsPEGPH20 administration resulted in degradation of HA in all tumour models tested, and resulted in increased VV in the 3 models tested. PEGPH20 +GEM + NAB led to enhanced tumour growth inhibition (TGI) compared to GEM+NAB in the BxPC3/HAS3 (104% v 70%, respectively, p<0.0001) and AsPC1/HAS3 (78% v 53%, respectively, p=0.0021) models. In CT26/HAS3, PEGPH20 +anti-CTLA4 resulted in enhanced TGI compared to anti-CTLA4 alone (p=0.002). PEGPH20 +anti-PD-L1 resulted in enhanced TGI compared to anti-PD-L1 alone 4 T1/HAS3 (93% v 18%, respectively, p<0.0001) and Pan02/HAS3 (50% v 5%, respectively, p<0.01).ConclusionThese studies demonstrate that the use of PEGPH20 to enzymatically remodel the TME in HA-high tumours may represent a novel approach for enhancing the efficacy of cancer therapeutics. A Phase 3 study of GEM and NAB ±PEGPH20 in patients with prospectively selected HA-high PDA is ongoing (NCT02715804).

Medial Tibial Stress Syndrome: Focused on Tibial Fascial-traction Theory and Prevention Strategies

PURPOSE This review article purpose to define and clarify the mechanism of MTSS, especially the tibial fascial-traction theory of MTSS. Additionally, the effectiveness of prevention strategies based on the tibial fascial-traction theory of MTSS was also assessed. BODY Shin splints is a well-known name of MTSS. It is commonly described as pain which occurs in the posteromedial border of the tibia caused by repetitive stresses. Some studies have addressed the tibial fascial-traction theory of MTSS as a possible mechanism in which traction forces are applied on the tibial periosteum though the soleal aponeurosis. Also, traction forces are applied on connective tissues by the soleus, tibialis posterior, and flexor digitorum longus. Prevention strategies are an avoidance of the repetitive stresses, running re-education such as an avoidance the forefoot strike patterns in runners who have risk factors for MTSS. Additionally, shoe modification such as motion control and stability shoes, and strengthening the ankle invertors are recommended. CONCLUSIONS This review article provided an overall review of the tibial-fascial traction theory of MTSS and recommendations for prevention strategies based on this theory. Keywords: Medial tibial stress syndrome / Prevention / Tibial fascial-traction theory