Vascularized Bone-Mimetic Hydrogel Constructs by 3D Bioprinting to Promote Osteogenesis and Angiogenesis.

Bone is a highly vascularized tissue with a unique and complex structure. Long bone consists of a peripheral cortical shell containing a network of channels for vascular penetration and an inner highly vascularized bone marrow space. Bioprinting is a powerful tool to enable rapid and precise spatial patterning of cells and biomaterials. Here we developed a two-step digital light processing technique to fabricate a bone-mimetic 3D hydrogel construct based on octacalcium phosphate (OCP), spheroids of human umbilical vein endothelial cells (HUVEC), and gelatin methacrylate (GelMA) hydrogels. The bone-mimetic 3D hydrogel construct was designed to consist of a peripheral OCP-containing GelMA ring to mimic the cortical shell, and a central GelMA ring containing HUVEC spheroids to mimic the bone marrow space. We further demonstrate that OCP, which is evenly embedded in the GelMA, stimulates the osteoblastic differentiation of mesenchymal stem cells. We refined the design of a spheroid culture device to facilitate the rapid formation of a large number of HUVEC spheroids, which were embedded into different concentrations of GelMA hydrogels. It is shown that the concentration of GelMA modulates the extent of formation of the capillary-like structures originating from the HUVEC spheroids. This cell-loaded hydrogel-based bone construct with a biomimetic dual ring structure can be potentially used for bone tissue engineering.

Systematic characterization of 3D-printed PCL/ß-TCP scaffolds for biomedical devices and bone tissue engineering: influence of composition and porosity.

This work aims at providing guidance through systematic experimental characterization, for the design of 3D printed scaffolds for potential orthopaedic applications, focusing on fused deposition modeling (FDM) with a composite of clinically available polycaprolactone (PCL) and ß-tricalcium phosphate (ß-TCP). First, we studied the effect of the chemical composition (0% to 60% ß-TCP/PCL) on the scaffold's properties. We showed that surface roughness and contact angle were respectively proportional and inversely proportional to the amount of ß-TCP, and that degradation rate increased with the amount of ceramic. Biologically, the addition of ß-TCP enhanced proliferation and osteogenic differentiation of C3H10. Secondly, we systematically investigated the effect of the composition and the porosity on the 3D printed scaffold mechanical properties. Both an increasing amount of ß-TCP and a decreasing porosity augmented the apparent Young's modulus of the 3D printed scaffolds. Third, as a proof-of-concept, a novel multi-material biomimetic implant was designed and fabricated for potential disk replacement.

Annulated isoxazoles via [3 + 2] cycloaddition of alkenyl bromides and oximoyl chlorides and Ag(I) promoted elimination.

Substituted salicylaldehydes are converted to fused tetracyclic isoxazoles through a synthetic sequence incorporating substitution of 2-bromo-2-cyclohexen-1-ol, formation of an oxime function, conversion to an oximoyl chloride, intramolecular [3 + 2] cycloaddition, and elimination of an equivalent of hydrogen bromide using silver(I) carbonate. Six examples of this sequence are presented.

Correct and Incorrect Recommendations for or against Fine Needle Biopsies of Hypofunctioning Thyroid Nodules: Performance of Different Ultrasound-based Risk Stratification Systems.

PURPOSE: To evaluate the recommendations for or against fine needle biopsy (FNB) of hypofunctioning thyroid nodules (TNs) using of five different Ultrasound (US) -based risk stratification systems (RSSs). METHODS: German multicenter study with 563 TNs (≥ 10 mm) in 534 patients who underwent thyroid US and surgery. All TNs were evaluated with ACR TI-RADS, EU-TIRADS, ATA, K-TIRADS 2016 and modified K-TIRADS 2021. A correct recommendation was defined as: malignant TN with recommendation for FNB (appropriate) or benign TN without recommendation for FNB (avoided). An incorrect recommendation was defined as: malignant TN without recommendation for FNB (missed) or benign TN with recommendation for FNB (unnecessary). RESULTS: ACR TI-RADS demonstrated the highest rate of correct (42.3 %) and lowest rate of incorrect recommendations (57.7 %). The other RRSs showed similar results for correct (26.5 %-35.7 %) and incorrect (64.3 %-73.5 %) recommendations. ACR TI-RADS demonstrated the lowest rate of unnecessary (73.4 %) and the highest rate of appropriate (26.6 %) FNB recommendation. For other RSSs, the rates of unnecessary and appropriate FNB were between 75.2 %-77.1 % and 22.9 %-24.8 %. The lowest rate of missed FNB (14.7 %) and the highest rate of avoided FNB (85.3 %) was found for ACR TI-RADS. For the other RSSs, the rates of missed and avoided FNB were between 17.8 %-26.9 % and 73.1 %-82.2 %. When the size cutoff was disregarded, an increase of correct recommendations and a decrease of incorrect recommendations was observed for all RSSs. CONCLUSION: The RSSs vary in their ability to correctly recommend for or against FNB. An understanding of the impact of nodule size cutoffs seems necessary for the future of TIRADS.

Thyroid Imaging Reporting and Data Systems: Applicability of the "Taller than Wide" Criterium in Primary/Secondary Care Units and the Role of Thyroid Scintigraphy.

BACKGROUND: To examine the applicability of the "taller than wide" (ttw) criterium for risk assessment of thyroid nodules (TNs) in primary/secondary care units and the role of thyroid scintigraphy therein. METHODS: German bicenter study performed in a setting of primary/secondary care. Patient recruitment and analysis in center A was conducted in a prospective manner. In center B, patient data were retrieved from a database that was originally generated by prospective data collection. TNs were assessed by ultrasound and thyroid scans, mostly fine needle biopsy and occasionally surgery and others. In center A, only patients who presented for the first time were included. The inclusion criterion was any TN ≥ 10 mm that had at least the following two sonographic risk features: solidity and a ttw shape. In center B, consecutive patients who had at least ttw and hypofunctioning nodules ≥ 10 mm were retrieved from the above-mentioned database. The risk of malignancy was determined according to a mixed reference standard and compared with literature data. RESULTS: In center A, 223 patients with 259 TNs were included into the study. For further analysis, 200 nodules with a reference standard were available. The overall malignancy rate was 2.5% (upper limit of the 95% CI: 5.1%). After the exclusion of scintigraphically hyperfunctioning nodules, the malignancy rate increased slightly to 2.8% (upper limit of the 95% CI: 5.7%). Malignant nodules exhibited sonographic risk features additional to solidity and ttw shape more often than benign ones. In addition to the exclusion of hyperfunctioning nodules, when considering only nodules without additional US risk features, i.e., exclusively solid and ttw-nodules, the malignancy rate decreased to 0.9% (upper limit 95% CI: 3.7%). In center B, from 58 patients, 58 ttw and hypofunctioning TNs on thyroid scans with a reference standard were available. Malignant nodules from center B were always solid and hypoechoic. The overall malignancy rate of hypofunctioning and ttw nodules was 21%, with the lower limit of the 95% CI (one-sided) being 12%. CONCLUSIONS: In primary/secondary care units, the lowest TIRADS categories for indicating FNB, e.g., applying one out of five sonographic risk features, may not be appropriate owing to the much lower a priori malignancy risk in TNs compared to tertiary/quaternary care units. Even the combination of two sonographic risk features, "solidity" and "ttw", may only be appropriate in a limited fashion. In contrast, the preselection of TNs according to hypofunctioning findings on thyroid scans clearly warranted FNB, even when applying only one sonographic risk criterion ("ttw"). For this reason, thyroid scans in TNs may not only be indicated to rule out hyperfunctioning nodules from FNB but also to rule in hypofunctioning ones.

A bioactive compliant vascular graft modulates macrophage polarization and maintains patency with robust vascular remodeling.

Conventional synthetic vascular grafts are associated with significant failure rates due to their mismatched mechanical properties with the native vessel and poor regenerative potential. Though different tissue engineering approaches have been used to improve the biocompatibility of synthetic vascular grafts, it is still crucial to develop a new generation of synthetic grafts that can match the dynamics of native vessel and direct the host response to achieve robust vascular regeneration. The size of pores within implanted biomaterials has shown significant effects on macrophage polarization, which has been further confirmed as necessary for efficient vascular formation and remodeling. Here, we developed biodegradable, autoclavable synthetic vascular grafts from a new polyurethane elastomer and tailored the grafts' interconnected pore sizes to promote macrophage populations with a pro-regenerative phenotype and improve vascular regeneration and patency rate. The synthetic vascular grafts showed similar mechanical properties to native blood vessels, encouraged macrophage populations with varying M2 to M1 phenotypic expression, and maintained patency and vascular regeneration in a one-month rat carotid interposition model and in a four-month rat aortic interposition model. This innovative bioactive synthetic vascular graft holds promise to treat clinical vascular diseases.

FDG-PET/CT for the early prediction of histopathological complete response to neoadjuvant chemotherapy in breast cancer patients: initial results.

BACKGROUND: Up to about one-quarter of patients treated with neoadjuvant chemotherapy do not adequately respond to the given treatment. By a differentiation between responders and non-responders ineffective toxic therapies can be prevented. PURPOSE: To retrospectively test if FDG-PET/CT is able to early differentiate between breast cancer lesions with pathological complete response (pCR) and lesions without pathological complete response (npCR) after two cycles of neoadjuvant chemotherapy (NACT). MATERIAL AND METHODS: In this retrospective study 26 breast cancer patients (mean age, 46.9 years ± 9.9 years) underwent a pre-therapeutic FDG-PET/CT scan and a subsequent FDG-PET/CT after the second cycle of NACT. Histopathology of resected specimen served as the reference standard. Maximum standardized uptake values (SUVmax) of cancer lesions before and after the second cycle of NACT were measured. Two evaluation algorithms were used: (a) pCR: Sinn Score 3 and 4, npCR: Sinn Score 0-2; (b) pCR: Sinn Score 4, npCR: Sinn Score 0-3. The absolute and relative decline of the SUVmax (ΔSUVmax, ΔSUVmax(%))was calculated. Differences of the SUVmax as well as of the SUVmax decline between pCR lesions and npCR lesions were tested for statistical significance P < 0.05. To identify the optimal cut-off value of ΔSUVmax(%) to differentiate between pCR lesions and npCR lesions a receiver-operating curve (ROC) analysis was performed. RESULTS: Using evaluation algorithm A the ΔSUVmax was 13.5 (pCR group) and 3.9 (npCR group) (P = 0.006); the ΔSUVmax(%) was 79% and 47%, respectively (P = 0.001). On ROC analysis an optimal cut-off ΔSUVmax(%) of 66% was found. Using evaluation algorithm B the ΔSUVmax was 17.5 (pCR group) and 4.9 (npCR group) (P = 0.013); the ΔSUVmax(%) was 89% and 51%, respectively (P = 0.003). On ROC analysis an optimal cut-off ΔSUVmax(%) of 88% was found. CONCLUSION: FDG-PET/CT may be able to early differentiate between pCR and npCR of primary breast cancer lesions after two cycles of NACT.

Hard templating of nanocrystalline titanium dioxide with chiral nematic ordering.

Anatase TiO(2) nanocrystals have been organized into high-surface-area (150-230 m(2) g(-1)) mesoporous films with long-range chiral nematic ordering. The chiral structure of the anatase films causes them to selectively reflect circularly polarized light and appear iridescent. These materials show replication of structural features found in the silica template on nanometer to millimeter length scales.

Probing the role of methyl methacrylate release from spacer materials in induced membrane bone healing.

In the induced membrane (IM) technique for bone reconstruction, a poly(methyl methacrylate) (PMMA) spacer is implanted to induce formation of a foreign body membrane around the defect site. Membrane development is essential for later bone grafting success, yet the mechanism by which the IM promotes bone regeneration remains unknown, as are the ways that spacer composition plays a role in the membrane's healing potential. This study investigated the impact of leached methyl methacrylate (MMA)-the major monomeric component of PMMA-on IM development. In vitro cell culture found that MMA elution did not impact endothelial cell or mesenchymal stem cell proliferation. For in vivo analysis, we advanced a streamlined rat femoral model to efficiently study the influence of spacer properties on IM characteristics. Comparison of membrane formation around polycaprolactone (PCL), MMA-eluting PCL (high-dose PCL-MMA and low-dose PCL-MMA), and surgical PMMA revealed robust membranes enveloped all groups after 4 weeks in vivo, with elevated expression of osteogenic bone morphogenetic protein-2 and angiogenic vascular endothelial growth factor compared with the surrounding muscle and bone tissues. Growth factor quantitation in IM tissue found no statistically significant difference between groups. New bone growth, vascularization, and CD163+ macrophage populations surrounding the polymer implants were also quantified; and blood vessel formation around high-dose PCL-MMA was found to be significantly decreased compared with PCL alone. To the best of our knowledge, these findings represent the first time that results have been obtained about the characteristics of membranes formed around PCL in the IM setting.

Introducing a Pole Concept for Nodule Growth in the Thyroid Gland: Taller-than-Wide Shape, Frequency, Location and Risk of Malignancy of Thyroid Nodules in an Area with Iodine Deficiency.

Purpose: (i) To examine the criterion taller-than-wide (TTW) for the sonographic assessment of thyroid nodules in areas of iodine deficiency in terms of frequency, anatomical distribution within the thyroid gland and risk of malignancy. (ii) To develop a model for nodule growth in the thyroid gland. Methods: German multicenter study consisting of two parts. In the prospective part, thyroid nodules were sonographically measured in all three dimensions, location within the thyroid gland and contact to a protrusion-like formation (horn) in the dorsal position of thyroid gland was noted. In addition, further sonographic features such as the composition, echogenity, margins and calcifications were investigated. All nodules from the prospective part were assessed for malignancy as part of clinical routine at the decision of the treating physician adhering to institutionally based algorithms. In the retrospective part, only nodules with fine needle aspiration and/or histology were included. The risk of malignancy in TTW nodules was determined by correlating them with cyotological and histological results. Results: Prospective part: out of 441 consecutively evaluated thyroid nodules, 6 were found to be malignant (1.4%, 95% CI 0.6-2.7%). Among the 74 TTW nodules (17%), 1 was malignant (1%, 95% CI 0-4%). TTW nodules were more often located in the dorsal half of the thyroid than non-TTW nodules (factor 2.3, p = 0.01, 95% CI 2.1-2.5) and more often located in close proximity to a horn than non-TTW nodules (factor 3.0, p = 0.01, 95% CI 2.4-3.8). Retrospective part: out of 1315 histologically and/or cytologically confirmed thyroid nodules, 163 TTW nodules were retrieved and retrospectively analyzed. A TTW nodule was 1.7 times more often benign when it was dorsal (95% CI 1.1-2.5) and 2.5 times more often benign when it was associated with a horn (95% CI 1.2-5.3). The overall probability of malignancy for TTW nodules was 38% (95% CI 30-46%) in this highly preselected patient group. Conclusion: TTW nodules are common in iodine deficient areas. They are often located in the dorsal half of the thyroid gland and are frequently associated with a dorsal protrusion-like formation (horn) of the thyroid. Obviously, the shape of benign nodules follows distinct anatomical preconditions within the thyroid gland. The frequency of TTW nodules and their predominant benignity can be explained by a pole concept of goiter growth. The difference between the low malignancy risk of TTW nodules found on a prospective basis and the high risk found retrospectively may be the result of a positive preselection in the latter.

Distribution of Functional Status of Thyroid Nodules and Malignancy Rates of Hyperfunctioning and Hypofunctioning Thyroid Nodules in Germany.

AIM: Thyroid scintigraphy enables the depiction of the functional status of thyroid nodules (TNs) with both, 99mTc-pertechnetate and 123Iodine. The functional status is relevant for diagnostic procedures for the differentiation of benign and malignant TNs. The aim of this study was to examine the current frequencies of hyper-, hypo- and isofunctioning TNs in Germany and to estimate the risk of malignancy with regard to functional status. METHODS: In 11 study centers, a minimum of 100 nodules per center were consecutively enrolled between July 2019 and April 2020. Inclusion criteria were: newly diagnosed nodule, nodule' size of 10 mm or more, thyroid scintigraphy. Exclusion criteria were: completely cystic TNs, patients with prior radioiodine therapy or thyroid surgery. The risk of malignancy was estimated for hyper- and hypofunctioning TNs. RESULTS: Overall, 849 patients (72 % women) with 1262 TNs were included. Patients' age ranged from 18 to 90 years. Most TNs were hypofunctioning (n=535, 42%) followed by isofunctioning TNs (n=488, 39%) and hyperfunctioning TNs (n=239, 19%). When only TNs with a maximum size of 2 cm or more were considered the rate of hyperfunctioning and hypofunctioning TNs increased (to 27% and 49%) while isofunctioning TNs decreased. Only one of all hyperfunctioning TNs was malignant. In hypofunctioning nodules, the malignancy rate was estimated at 10%. CONCLUSION: In Germany, the proportion of hyperfunctioning TNs is approximately 20% and increases in larger TNs to up to 27%. Due to the low risk of malignancy in hyperfunctioning TNs, no further procedures to rule out malignancy are necessary. The risk of malignancy of hypofunctioning TNs is significantly higher. Thus, a thyroid scintigraphy is a useful diagnostic tool in Germany.

Clinical applications of 124I-PET/CT in patients with differentiated thyroid cancer.

(124)I-PET/CT has a high clinical potential in patients with differentiated thyroid cancer (DTC). Two aspects deserve special mention: staging of recurrent or residual disease and pretherapy dosimetry. Used in combination (124)I-PET and CT allows foci of highly specific (124)I uptake to be localized with a low radiation dose, which is specifically important in pretherapy diagnostics. In addition in the combination of FDG-PET and CT non-iodine-avid lesions may be detected and may be discriminated from simultaneously occurring iodine-positive lesions. In clinical applications, the pretherapy (124)I-PET dosimetry may result in a significant alteration in the therapeutic procedure compared to standard therapy using fixed therapeutic activities. In this context, (124)I-PET dosimetry is a useful procedure especially in advanced DTC, and allows the administration of safer and more effective radioiodine activities as well as earlier multimodal interventions compared to standard empirical protocols. This review summarizes the clinical data on (124)I-PET/CT in patients with DTC, and addresses future prospects.

Diagnosis and dosimetry in differentiated thyroid carcinoma using 124I PET: comparison of PET/MRI vs PET/CT of the neck.

PURPOSE: This study compares intrinsically coregistered 124I positron emission tomography (PET) and CT (PET/CT) and software coregistered 124I PET and MRI (PET/MRI) images for the diagnosis and dosimetry of thyroid remnant tissues and lymph node metastases in patients with differentiated thyroid carcinoma (DTC). METHODS: After thyroidectomy, 33 high-risk DTC patients (stage III or higher) received 124I PET/CT dosimetry prior to radioiodine therapy to estimate the absorbed dose to lesions and subsequently underwent a contrast-enhanced MRI examination of the neck. Images were evaluated by two experienced nuclear medicine physicians and two radiologists to identify the lesions and to categorize their presumable provenience, i.e. thyroid remnant tissue (TT), lymph node metastasis (LN) and inconclusive tissue. The categorization and dosimetry of lesions was initially performed with PET images alone (PET only). Subsequently lesions were reassessed including the CT and MRI data. RESULTS: The analyses were performed on a patient and on a lesion basis. Patient-based analyses showed that 26 of 33 (79%) patients had at least one lesion categorized as TT on PET only. Of these patients, 11 (42%) and 16 (62%) had a morphological correlate on CT and MRI, respectively, in at least one TT PET lesion. Twelve patients (36%) had at least one lesion classified as LN on PET only. Nine (75%) of these patients had a morphological correlate on both CT and MRI in at least one LN PET lesion. Ten patients (30%) showed at least one lesion on PET only classified as inconclusive. The classification was changed to a clear classification in two patients (two LN) by CT and in four (two TT, two LN) patients by MRI. Lesion-based analyses (n=105 PET positive lesions) resulted in categorization as TT in 61 cases (58%), 16 (26%) of which had a morphological correlate on CT and 33 (54%) on MRI. A total of 29 lesions (27%) were classified as LN on PET, 18 (62%) of which had a morphological correlate on CT and 24 (83%) on MRI. In 16 lesions (15%) PET alone allowed no definite categorization. Categorization was achieved with the aid of CT and MRI, respectively, in five (one TT, four LN) and in six (two TT, four LN) lesions. In direct comparison, 23 lesions were not discernible on CT but clearly visible on MRI, 15 of which were smaller than 10 mm and about two thirds were classified as TT. Redoing dosimetry based on the volume information from MRI for these small lesions would have changed the initial therapy regime in five patients. These patients would have received (131)I therapy with standardized activities of 3.7 GBq or 7.4 GBq instead of activities higher than 10 GBq and would have benefited from reduced radiation exposure. CONCLUSION: PET/MRI is superior to PET/CT in terms of tracing back a PET focus to a morphological correlate. For this reason PET/MRI enhances diagnostic certainty for lesions<10 mm and improves pretherapeutic lesion dosimetry in DTC.

Comparison of FDG-PET/CT and bone scintigraphy for detection of bone metastases in breast cancer.

BACKGROUND: Bone scintigraphy is the standard procedure for the detection of bone metastases in breast cancer patients. FDG-PET/CT has been reported to be a sensitive tool for tumor staging in different malignant diseases. However, its accuracy for the detection of bone metastases has not been compared to bone scintigraphy. PURPOSE: To compare whole-body FDG-PET/CT and bone scintigraphy for the detection of bone metastases on a lesion basis in breast cancer patients. MATERIAL AND METHODS: Twenty-nine consecutive women (mean age 58 years, range 35-78 years) with histologically proven breast cancer were assessed with bone scintigraphy and whole-body FDG-PET/CT. Twenty-one patients (72%) were suffering from primary breast cancer and eight patients (28%) were in aftercare with a history of advanced breast cancer. Both imaging procedures were assessed for bone metastases by a radiologist and a nuclear medicine physician. Concordant readings between bone scintigraphy and FDG-PET/CT were taken as true. Discordant readings were verified with additional MRI imaging in all patients and follow-up studies in most patients. RESULTS: A total of 132 lesions were detected on bone scintigraphy, FDG-PET/CT or both. According to the reference standard, 70/132 lesions (53%) were bone metastases, 59/132 lesions (45%) were benign, and three lesions (2%) remained unclear. The sensitivity of bone scintigraphy was 76% (53/70) compared to 96% (67/70) for FDG-PET/CT. The specificity of bone scintigraphy and FDG-PET/CT was 95% (56/59) and 92% (54/59), respectively. According to the reference standard bone metastases were present in eight out of the 29 patients (28%), whereas 20 patients (69%) were free of bone metastases. One (3%) patient had inconclusive readings on both modalities as well as on MRI and follow-up studies. Bone scintigraphy and FDG-PET/CT correctly identified seven out of eight patients with bone metastases and 20 out of 20 patients free of metastases. CONCLUSION: On a lesion-basis whole-body FDG-PET/CT is more sensitive and equally specific for the detection of bone metastases compared with bone scintigraphy.

Regenerative Approaches for the Treatment of Large Bone Defects.

A variety of engineered materials have gained acceptance in orthopedic practice as substitutes for autologous bone grafts, although the regenerative efficacy of these engineered grafts is still limited compared with that of transplanted native tissues. For bone defects greater than 4-5 cm, however, common bone grafting procedures are insufficient and more complicated surgical interventions are required to repair and regenerate the damaged or missing bone. In this review, we describe current grafting materials and surgical techniques for the reconstruction of large bone defects, followed by tissue engineering (TE) efforts to develop improved therapies. Particular emphasis is placed on graft vascularization, because for both autologous bone and engineered alternatives, achieving adequate vascular development within the regenerating bone tissues remains a significant challenge in the context of large bone defects. To this end, TE and surgical strategies to induce development of a vasculature within bone grafts are discussed. Impact statement This review aims to present an accessible and thorough overview of current orthopedic surgical techniques as well as bone tissue engineering and vascularization strategies that might one day offer improvements to clinical therapies for the repair of large bone defects. We consider the lessons that clinical orthopedic reconstructive practices can contribute to the push toward engineered bone.

Diagnostic Performance of Kwak, EU, ACR, and Korean TIRADS as Well as ATA Guidelines for the Ultrasound Risk Stratification of Non-Autonomously Functioning Thyroid Nodules in a Region with Long History of Iodine Deficiency: A German Multicenter Trial.

Germany has a long history of insufficient iodine supply and thyroid nodules occur in over 30% of the adult population, the vast majority of which are benign. Non-invasive diagnostics remain challenging, and ultrasound-based risk stratification systems are essential for selecting lesions requiring further clarification. However, no recommendation can yet be made about which system performs the best for iodine deficiency areas. In a German multicenter approach, 1211 thyroid nodules from 849 consecutive patients with cytological or histopathological results were enrolled. Scintigraphically hyperfunctioning lesions were excluded. Ultrasound features were prospectively recorded, and the resulting classifications according to five risk stratification systems were retrospectively determined. Observations determined 1022 benign and 189 malignant lesions. The diagnostic accuracies were 0.79, 0.78, 0.70, 0.82, and 0.79 for Kwak Thyroid Imaging Reporting and Data System (Kwak-TIRADS), American College of Radiology (ACR) TI-RADS, European Thyroid Association (EU)-TIRADS, Korean-TIRADS, and American Thyroid Association (ATA) Guidelines, respectively. Receiver Operating Curves revealed Areas under the Curve of 0.803, 0.795, 0.800, 0.805, and 0.801, respectively. According to the ATA Guidelines, 135 thyroid nodules (11.1%) could not be classified. Kwak-TIRADS, ACR TI-RADS, and Korean-TIRADS outperformed EU-TIRADS and ATA Guidelines and therefore can be primarily recommended for non-autonomously functioning lesions in areas with a history of iodine deficiency.

Combining a Vascular Bundle and 3D Printed Scaffold with BMP-2 Improves Bone Repair and Angiogenesis.

Vascularization is currently considered the biggest challenge in bone tissue engineering due to necrosis in the center of large scaffolds. We established a new expendable vascular bundle model to vascularize a three-dimensional printed channeled scaffold with and without bone morphogenetic protein-2 (BMP-2) for improved healing of large segmental bone defects. Bone formation and angiogenesis in an 8 mm critical-sized bone defect in the rat femur were significantly promoted by inserting a bundle consisting of the superficial epigastric artery and vein into the central channel of a large porous polycaprolactone scaffold. Vessels were observed sprouting from the vascular bundle inserted in the central tunnel. Although the regenerated bone volume in the group receiving the scaffold and vascular bundle was similar to that of the healthy femur, the rate of union of the group was not satisfactory (25% at 8 weeks). BMP-2 delivery was found to promote not only bone formation but also angiogenesis in the critical-sized bone defects. Both insertion of the vascular bundle alone and BMP-2 loading alone induced comparable levels of angiogenesis and when used in combination, significantly greater vascular volume was observed. These findings suggest a promising new modality of treatment in large bone defects. Level of Evidence: Therapeutic level I. Impact statement Vascularization is currently the main challenge in bone tissue engineering. The combination of a vascular bundle and an osteoinductive three-dimensional printed graft significantly improved and accelerated bone regeneration and angiogenesis in critical-sized large bone defects, suggesting a promising new modality of treatment in large bone defects.

Effect of Zinc Oxide Nanoparticle Addition to Polycaprolactone Periodontal Membranes on Antibacterial Activity and Cell Viability.

During the design of membranes for guided tissue regeneration (GTR) to treat periodontal diseases, infection of the exposed membranes and postoperative complications can be prevented by increasing bacterial resistance. This study evaluated the antibacterial activity of PCL/ZnO membranes and their effect on cell viability via addition of antibacterial zinc oxide (ZnO) nanoparticles to a biocompatible and biodegradable material such as polycaprolactone (PCL). Neat PCL membranes and PCL/ZnO membranes containing 0.5 wt.% and 5 wt.% ZnO were produced, and divided into PCL (0% ZnO), LZ (0.5 wt.% ZnO), and HZ (5 wt.% ZnO) groups, respectively. The surface characteristics of the membranes including morphological features and changes in composition were analyzed. Adhesion of bacteria, including Streptococcus mutans and Porphyromonas gingi-valis, was analyzed using a crystal violet assay. The proliferation of MC3T3-E1 osteoblasts was evaluated using a WST-8 assay. Significant differences were analyzed using the Kruskal-Wallis test (P < 0.05). The results of groups were compared using the Mann-Whitney test (P < 0.017). ZnO nanoparticles were dispersed in the PCL matrix of PCL/ZnO membranes. Compared with neat PCL membranes, their ability to form crystals decreased and their amorphous structure increased. The adhesion of S. mutans and P. gingivalis in the LZ and HZ groups containing ZnO was significantly decreased compared with that of the neat PCL membranes (P < 0.05). No significant differences were observed in the proliferation of MC3T3-E1 cells between the PCL/ZnO membranes and the neat PCL membranes both on days 2 and 5 of culture (P > 0.05). This study has demonstrated that the PCL membranes carrying the ZnO nanoparticles inhibited bacterial adhesion without affecting the viability of osteoblasts, suggesting the potential application of ZnO in GTR to increase antibacterial activity of membranes.

Investigation of a Prevascularized Bone Graft for Large Defects in the Ovine Tibia.

In vivo bioreactors are a promising approach for engineering vascularized autologous bone grafts to repair large bone defects. In this pilot parametric study, we first developed a three-dimensional (3D) printed scaffold uniquely designed to accommodate inclusion of a vascular bundle and facilitate growth factor delivery for accelerated vascular invasion and ectopic bone formation. Second, we established a new sheep deep circumflex iliac artery (DCIA) model as an in vivo bioreactor for engineering a vascularized bone graft and evaluated the effect of implantation duration on ectopic bone formation. Third, after 8 weeks of implantation around the DCIA, we transplanted the prevascularized bone graft to a 5 cm segmental bone defect in the sheep tibia, using the custom 3D printed bone morphogenic protein 2 (BMP-2) loaded scaffold without prior in vivo bioreactor maturation as a control. Analysis by micro-computed tomography and histomorphometry found ectopic bone formation in BMP-2 loaded scaffolds implanted for 8 and 12 weeks in the iliac pouch, with greater bone formation occurring after 12 weeks. Grafts transplanted to the tibial defect supported bone growth, mainly on the periphery of the graft, but greater bone growth and less soft tissue invasion was observed in the avascular BMP-2 loaded scaffold implanted directly into the tibia without prior in vivo maturation. Histopathological evaluation noted considerably greater vascularity in the bone grafts that underwent in vivo maturation with an inserted vascular bundle compared with the avascular BMP-2 loaded graft. Our findings indicate that the use of an initial DCIA in vivo bioreactor maturation step is a promising approach to developing vascularized autologous bone grafts, although scaffolds with greater osteoinductivity should be further studied. Impact statement This translational pilot study aims at combining a tissue engineering scaffold strategy, in vivo prevascularization, and a modified transplantation technique to accelerate large segmental bone defect repair. First, we three-dimensional (3D) printed a 5 cm scaffold with a unique design to facilitate vascular bundle inclusion and osteoinductive growth factor delivery. Second, we established a new sheep deep circumflex iliac artery model as an in vivo bioreactor for prevascularizing the novel 3D printed osteoinductive scaffold. Subsequently, we transplanted the prevascularized bone graft to a clinically relevant 5 cm segmental bone defect in the sheep tibia for bone regeneration.

Osteoinductive 3D printed scaffold healed 5 cm segmental bone defects in the ovine metatarsus.

Autologous bone grafts are considered the gold standard grafting material for the treatment of nonunion, but in very large bone defects, traditional autograft alone is insufficient to induce repair. Recombinant human bone morphogenetic protein 2 (rhBMP-2) can stimulate bone regeneration and enhance the healing efficacy of bone grafts. The delivery of rhBMP-2 may even enable engineered synthetic scaffolds to be used in place of autologous bone grafts for the treatment of critical size defects, eliminating risks associated with autologous tissue harvest. We here demonstrate that an osteoinductive scaffold, fabricated by combining a 3D printed rigid polymer/ceramic composite scaffold with an rhBMP-2-eluting collagen sponge can treat extremely large-scale segmental defects in a pilot feasibility study using a new sheep metatarsus fracture model stabilized with an intramedullary nail. Bone regeneration after 24 weeks was evaluated by micro-computed tomography, mechanical testing, and histological characterization. Load-bearing cortical bridging was achieved in all animals, with increased bone volume observed in sheep that received osteoinductive scaffolds compared to sheep that received an rhBMP-2-eluting collagen sponge alone.