Citations

Background: Since healing of anterior cruciate ligament (ACL) grafts occurs by formation of a fibrovascular scar-tissue interface rather than by reformation of the native fibrocartilage transition zone, the purpose of our study was to examine expression of various signaling molecules and transcription factors that are known to be involved in embryologic insertion-site development following ACL reconstruction. We also aimed to characterize a murine model of ACL reconstruction to allow future study of the molecular mechanisms of healing. Methods: Seventy-nine mice underwent reconstruction of the ACL with autograft. Healing was assessed using histology in 12 mice and quantitative real-time polymerase chain reaction (qRT-PCR) gene-expression analysis in 3 mice at 1 week postoperatively (Group-1 mice) and by biomechanical analysis in 7, histological analysis in 7, immunohistochemical analysis in 5, microcomputed tomography analysis in 5, and qRT-PCR analyses in 8 at 2 weeks (Group-2 mice) and 4 weeks (Group-3 mice) postoperatively. Fifteen additional mice did not undergo surgery and were used for biomechanical (7 mice), qRT-PCR (3 mice), and immunohistochemical (5 mice) analyses to obtain baseline data for the native ACL. Results: Histological analysis demonstrated healing by formation of fibrovascular tissue at the tendon-bone interface. Immunohistochemical analysis showed a positive expression of proteins in the Indian hedgehog, Wnt, and parathyroid hormone-related protein (PTHrP) pathways. There was minimal Sox-9 expression. Gene-expression analysis showed an initial increase in markers of tissue repair and turnover, followed by a subsequent decline. Mean failure force and stiffness of the native ACL were 5.60 N and 3.44 N/mm, respectively. Mean failure force and stiffness were 1.29 N and 2.28 N/mm, respectively, in Group 2 and were 1.79 N and 2.59 N/mm, respectively, in Group 3, with 12 of 14 failures in these study groups occurring by tunnel pull-out. Conclusions: The spatial and temporal pattern of expression of signaling molecules that direct embryologic insertion-site formation was not adequate to restore the structure and composition of the native insertion site. Clinical Relevance: Development of a murine model to study ACL reconstruction will allow the use of transgenic animals to investigate the cellular, molecular, and biomechanical aspects of tendon-to-bone healing following ACL reconstruction, ultimately suggesting methods to improve healing in patients.

Background: Extracellular vesicles (EVs) released from mesenchymal stem/stromal cells (MSCs) mediate their paracrine effect, but their efficacy to protect the microcirculation of the kidney is unknown. Using a novel swine model of unilateral renovascular disease (RVD) complicated by metabolic syndrome (MetS), we tested the hypothesis that EVs would attenuate renal microvascular loss. Methods: Four groups of pigs ( n = 7 each) were studied after 16 weeks of diet-induced MetS and RVD (MetS+RVD), MetS+RVD treated 4 weeks earlier with a single intra-renal delivery of EVs harvested from autologous adipose tissue-derived MSCs, and Lean and MetS Sham controls. Stenotic-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were measured in-vivo (fast CT), whereas EV characteristics, renal microvascular architecture (micro-CT), and injury pathways were studied ex-vivo. Results: mRNA sequencing and proteomic analysis revealed that EVs are packed with several pro-angiogenic genes and proteins, such as vascular endothelial growth factor. Labeled EVs were detected in the stenotic kidney 4 weeks after injection internalized by tubular and endothelial cells. EVs restored renal expression of angiogenic factors and improved cortical microvascular and peritubular capillary density. Renal apoptosis, oxidative stress, tubular injury, and fibrosis were also attenuated in EV-treated pigs. RBF and GFR decreased in MetS+RVD compared with MetS, but normalized in MetS+RVD+EVs. Conclusions: Intra-renal delivery of MSC-derived EVs bearing pro-angiogenic properties restored the renal microcirculation and in turn hemodynamics and function in chronic experimental MetS+RVD. Our study suggests a novel therapeutic potential for MSC-derived EVs in restoring renal hemodynamics in experimental MetS+RVD.

SummaryWe evaluated the association of Human Pegivirus (HPgV) viraemia with risk of developing lymphoma, overall and by major subtypes. Because this virus has also been associated with better prognosis in the setting of co‐infection with human immunodeficiency virus, we further assessed the association of HPgV with prognosis. We used risk factor data and banked plasma samples from 2094 lymphoma cases newly diagnosed between 2002 and 2009 and 1572 frequency‐matched controls. Plasma samples were tested for HPgV RNA by reverse transcription polymerase chain reaction (RT‐PCR), and those with RNA concentrations <5000 genome equivalents/ml were confirmed using nested RT‐PCR methods. To assess the role of HPgV in lymphoma prognosis, we used 2948 cases from a cohort study of newly diagnosed lymphoma patients (included all cases from the case‐control study). There was a positive association of HPgV viraemia with risk of lymphoma overall (Odds ratio = 2·14; 95% confidence interval [CI] 1·63–2·80; P < 0·0001), and for all major subtypes except Hodgkin lymphoma and chronic lymphocytic leukaemia/small lymphocytic lymphoma, and this was not confounded by other lymphoma risk factors. In contrast, there was no association of HPgV viraemia with event‐free survival (Hazard ratio [HR] = 1·00; 95% CI 0·85–1·18) or overall survival (HR = 0·97; 95% CI 0·79–1·20) for lymphoma overall, or any of the subtypes. These data support the hypothesis for a role of HPgV in the aetiology of multiple lymphoma subtypes.

Objectives The ability to determine the severity of renal fibrosis, which is involved in most chronic kidney diseases, may be beneficial for monitoring disease progression and management. The aim of this study was to assess a new method involving gold nanoparticles conjugated to an anti-collagen-I antibody (Co-I-AuNPs) as a computed tomography (CT) imaging contrast for the evaluation of renal fibrosis in situ. Materials and Methods Gold nanoparticles conjugated to an anti-collagen-I antibody were prepared using gold chloride reduction with sodium citrate and coated with polyethylene glycol (PEG), and their size was determined by electron microscopy and nanoparticle tracking analysis. Anti-collagen-I antibody was then conjugated to PEG-SH/COOH on the AuNP surface. The success of antibody conjugation was tested in vitro using collagen-coated plate and mouse stenotic kidney sections and in vivo using micro-CT and multidetector CT imaging. Results Bare AuNPs were 18.7 ± 0.6 nm and PEG-coated AuNPs were 45.3 ± 0.1 nm in size. In vitro, Co-I-AuNPs specifically bound to both a collagen-coated plate and mouse fibrotic kidneys. Furthermore, the stenotic mouse kidney showed increased Co-I-AuNPs retention compared with the contralateral kidney (59.3 ± 5.1 vs 45.1 ± 1.7 HU, P = 0.05), which correlated with its collagen deposition. Micro-CT also detected gold signals in situ in the Co-I-AuNP-injected kidney, which colocalized with histological trichrome staining. Conclusion Gold nanoparticles conjugated to an anti-collagen-I antibody are able to visualize kidney fibrosis in vitro and in situ and may be useful for nondestructive quantification of tissue fibrosis.

Abstract Background Previous genome-wide association studies (GWAS) have identified 42 loci (P < 5 × 10−8) associated with risk of colorectal cancer (CRC). Expanded consortium efforts facilitating the discovery of additional susceptibility loci may capture unexplained familial risk. Methods We conducted a GWAS in European descent CRC cases and control subjects using a discovery–replication design, followed by examination of novel findings in a multiethnic sample (cumulative n = 163 315). In the discovery stage (36 948 case subjects/30 864 control subjects), we identified genetic variants with a minor allele frequency of 1% or greater associated with risk of CRC using logistic regression followed by a fixed-effects inverse variance weighted meta-analysis. All novel independent variants reaching genome-wide statistical significance (two-sided P < 5 × 10−8) were tested for replication in separate European ancestry samples (12 952 case subjects/48 383 control subjects). Next, we examined the generalizability of discovered variants in East Asians, African Americans, and Hispanics (12 085 case subjects/22 083 control subjects). Finally, we examined the contributions of novel risk variants to familial relative risk and examined the prediction capabilities of a polygenic risk score. All statistical tests were two-sided. Results The discovery GWAS identified 11 variants associated with CRC at P < 5 × 10−8, of which nine (at 4q22.2/5p15.33/5p13.1/6p21.31/6p12.1/10q11.23/12q24.21/16q24.1/20q13.13) independently replicated at a P value of less than .05. Multiethnic follow-up supported the generalizability of discovery findings. These results demonstrated a 14.7% increase in familial relative risk explained by common risk alleles from 10.3% (95% confidence interval [CI] = 7.9% to 13.7%; known variants) to 11.9% (95% CI = 9.2% to 15.5%; known and novel variants). A polygenic risk score identified 4.3% of the population at an odds ratio for developing CRC of at least 2.0. Conclusions This study provides insight into the architecture of common genetic variation contributing to CRC etiology and improves risk prediction for individualized screening.

Lesser degrees of terminal duct lobular unit (TDLU) involution, as reflected by higher numbers of TDLUs and acini/TDLU, are associated with elevated breast cancer risk. In rodent models, the insulin‐like growth factor (IGF) system regulates involution of the mammary gland. We examined associations of circulating IGF measures with TDLU involution in normal breast tissues among women without precancerous lesions. Among 715 Caucasian and 283 African American (AA) women who donated normal breast tissue samples to the Komen Tissue Bank between 2009 and 2012 (75% premenopausal), serum concentrations of IGF‐I and binding protein (IGFBP)‐3 were quantified using enzyme‐linked immunosorbent assay. Hematoxilyn and eosin‐stained tissue sections were assessed for numbers of TDLUs (“TDLU count”). Zero‐inflated Poisson regression models with a robust variance estimator were used to estimate relative risks (RRs) for association of IGF measures (tertiles) with TDLU count by race and menopausal status, adjusting for potential confounders. AA (vs. Caucasian) women had higher age‐adjusted mean levels of serum IGF‐I (137 vs. 131 ng/mL, p = 0.07) and lower levels of IGFBP‐3 (4165 vs. 4684 ng/mL, p < 0.0001). Postmenopausal IGFBP‐3 was inversely associated with TDLU count among AA (RRT3vs.T1 = 0.49, 95% CI = 0.28–0.84, p‐trend = 0.04) and Caucasian (RRT3vs.T1=0.64, 95% CI = 0.42–0.98, p‐trend = 0.04) women. In premenopausal women, higher IGF‐I:IGFBP‐3 ratios were associated with higher TDLU count in Caucasian (RRT3vs.T1=1.33, 95% CI = 1.02–1.75, p‐trend = 0.04), but not in AA (RRT3vs.T1=0.65, 95% CI = 0.42–1.00, p‐trend = 0.05), women. Our data suggest a role of the IGF system, particularly IGFBP‐3, in TDLU involution of the normal breast, a breast cancer risk factor, among Caucasian and AA women.

Background: Following anterior cruciate ligament (ACL) reconstruction, the mechanical loading of the tissues has a significant impact on tendon-to-bone healing. The purpose of this study was to determine the effect of the timing of the initiation of mechanical loading on healing of a tendon graft in a bone tunnel. Methods: ACL reconstruction using a flexor tendon autograft was performed in 56 mice randomized to 4 groups with differing times to initiation of postoperative mechanical loading: (1) immediate, (2) 5 days, (3) 10 days, or (4) 21 days following surgery. An external fixator was placed across the knee at the time of surgery and removed when mechanical loading was scheduled to commence. Following removal of the external fixator, animals were permitted free, unrestricted cage activity. All mice were killed on postoperative day 28, and tendon-to-bone healing was assessed by biomechanical testing, microcomputed tomography (micro-CT), and histological analysis. Results: The mean failure force (and standard deviation) of the reconstructed ACL at the time of sacrifice was highest for Group 2 (3.29 ± 0.68 N) compared with Groups 1, 3, and 4 (p = 0.008). Micro-CT bone volume fraction was greatest for Group 2 in the femoral tunnel (p = 0.001), tibial tunnel (p = 0.063), and both bones (p < 0.001). Similarly, histological analysis demonstrated a narrower scar tissue interface and increased direct contact at the tendon-bone interface (p = 0.012) for Group 2. Conclusions: Following ACL reconstruction, a defined period of immobilization without weight-bearing appears to improve biomechanical strength of the healing tendon-bone interface, while prolonged periods without mechanical load and motion decrease the ultimate load to failure in this murine model. Clinical Relevance: The ideal period of restricted weight-bearing and motion following ACL reconstruction remains undefined. In a murine model, improved healing was noted for animals immobilized for a brief period of 5 days. This work may serve as an initial step in determining the ideal time period in a clinical population.