Tissue-Engineered Model of Human Osteolytic Bone Tumor.

Ewing's sarcoma (ES) is a poorly differentiated pediatric tumor of aggressive behavior characterized by propensity to metastasize to bone. Interactions between the tumor and bone cells orchestrate a vicious cycle in which tumor cells induce osteoclast differentiation and activation to cause osteolytic lesions, broken bones, pain, and hypercalcemia. The lack of controllable models that can recapitulate osteolysis in ES impedes the development of new therapies and limits our understanding of how tumor cells invade bone. In response to this need, tissue-engineered models are now being developed to enable quantitative, predictive studies of human tumors. In this study, we report a novel bioengineered model of ES that incorporates the osteolytic process. Our strategy is based on engineering human bone containing both osteoclasts and osteoblasts within three-dimensional mineralized bone matrix. We show that the bone matrix is resorbed by mature osteoclasts while the new bone matrix is formed by osteoblasts, leading to calcium release and bone remodeling. Introduction of ES cell aggregates into the bone niche induced decreases in bone density, connectivity, and matrix deposition. Additionally, therapeutic reagents, such as zoledronic acid, which have demonstrated efficacy in ES treatment, inhibited bone resorption mediated by osteoclasts in the tumor model.

Recapitulating the Size and Cargo of Tumor Exosomes in a Tissue-Engineered Model.

There is a growing interest in the pivotal role of exosomes in cancer and in their use as biomarkers. However, despite the importance of the microenvironment for cancer initiation and progression, monolayer cultures of tumor cells still represent the main in vitro source of exosomes. As a result, their environmental regulation remains largely unknown. Here, we report a three-dimensional tumor model for studying exosomes, using Ewing's sarcoma type 1 as a clinically relevant example. The bioengineered model was designed based on the hypothesis that the 3-dimensionality, composition and stiffness of the tumor matrix are the critical determinants of the size and cargo of exosomes released by the cancer cells. We analyzed the effects of the tumor microenvironment on exosomes, and the effects of exosomes on the non-cancer cells from the bone niche. Exosomes from the tissue-engineered tumor had similar size distribution as those in the patients' plasma, and were markedly smaller than those in monolayer cultures. Bioengineered tumors and the patients' plasma contained high levels of the Polycomb histone methyltransferase EZH2 mRNA relatively to their monolayer counterparts. Notably, EZH2 mRNA, a potential tumor biomarker detectable in blood plasma, could be transferred to the surrounding mesenchymal stem cells. This study provides the first evidence that an in vitro culture environment can recapitulate some properties of tumor exosomes.

Modeling tumor microenvironments using custom-designed biomaterial scaffolds.

The dominant roles of the tumor microenvironment in regulating tumor formation, progression, and metastasis have driven the application of tissue engineering strategies in cancer biology. Highly dynamic and reciprocal communication of tumor cells with their surroundings suggests that studying cancer in custom-designed biomaterial scaffolds may lead to novel therapeutic targets and therapeutic regimens more reliably than traditional monolayer tissue culture models. As tissue engineering becomes progressively more successful in recapitulating the native tumor environment, critical insights into mechanisms of tumor resistance may be elucidated, to impact clinical practice, drug development, and biological research. We review here the recent developments in the use of custom-designed biomaterial scaffolds for modeling human tumors.

Fabrication and properties of acellular porcine anulus fibrosus for tissue engineering in spine surgery.

BACKGROUND: Over the last few years, new treatments for a damaged intervertebral disc (IVD) have included strategies to repair, replace, or regenerate the degenerative disc. However, these techniques are likely to have limited success, due to insufficiently effective means to address the damaged anulus fibrosus (AF). Here, we try to develop a bioprocess method for decellularization of the xenogeneic AF tissue, with a view to developing a scaffold as a potential candidate for clinical application in spinal surgery. METHODS: Porcine AFs were decellularized using freeze-thaw cycles, followed by various combined treatments with 0.1% sodium dodecyl sulfate (SDS) and nucleases. RESULTS: Hematoxylin and eosin (H & E) staining showed that decellularization was achieved through the decellularization protocols. Biochemical analyses revealed 86% reduction in DNA, but only 15.9% reduction in glycosaminoglycan (GAG) content, with no significant difference in the hydroxyproline content. There was no appreciable cytotoxicity of the acellular AF. Biomechanical testing of the acellular AF found no significant decline in stiffness or Young's modulus. CONCLUSIONS: Porcine AF tissues were effectively decellularized with the preservation of biologic composition and mechanical properties. These results demonstrate that acellular AF scaffolds would be a potential candidate for clinical application in spinal surgery.

Fruit and vegetable intake and bone mass in Chinese adolescents, young and postmenopausal women.

OBJECTIVE: Previous studies showed an inconsistent association of fruit and vegetable consumption with bone health. We assessed the associations in Chinese adolescents, young and postmenopausal women. DESIGN: A cross-sectional study conducted in China during July 2009 to May 2010. SETTING: Bone mineral density (BMD) and content (BMC) at the whole body, lumbar spine and left hip were measured with dual-energy X-ray absorptiometry. Dietary intakes were assessed using an FFQ. All these values were separately standardized into Z-scores in each population subgroup. SUBJECTS: One hundred and ten boys and 112 girls (11-14 years), 371 young women (20-34 years, postpartum within 2 weeks) and 333 postmenopausal women (50-70 years). RESULTS: After adjustment for potential covariates, analysis of covariance showed a significantly positive association between fruit intake and BMD and BMC in all participants combined (P-trend: < 0.001 to 0.002). BMD Z-score increased by 0.25 (or 2.1 % of the mean), 0.22 (3.5 %), 0.23 (3.0 %) and 0.25 (3.5 %), and BMC Z-score increased by 0.33 (5.7 %), 0.25 (5.8 %), 0.34 (5.9 %) and 0.29 (4.7 %), at the total body, lumbar spine, total hip and femoral neck in participants belonging to the top tertile compared with the bottom tertile of fruit intake (all P < 0.05), respectively. There was no significant association between vegetable intake and bone mass at all bone sites studied except for total body BMD (P = 0.030). Relatively more pronounced effects were observed in boys and postmenopausal women. CONCLUSION: Our findings add to the existing evidence that fruits and vegetables may have a bone sparing effect.

Bad science [perspectives on graduate life].

On a picturesque summer day a few months ago, a friend and I were walking along a New Jersey boardwalk when we ran into a group of older women who recently retired from nursing. Casual conversation over a beautifully staged beach wedding taking place that afternoon turned naturally into a discussion of our various professions. Upon hearing that my friend was in medical school, the women began shrieking with a level of delight and adoration that could only be matched by his own mother's overflowing pride. In his embarrassment, my friend quickly attempted to shift attention onto me by divulging that I was also in school to become a doctor-the kind that does science and research. Their faces immediately belied their bewilderment over why they should care about this different kind of doctor, and the blatant indifference on their comically over expressive faces was so jarring that I could not contain my own hysterical laughter.

Hybrid gel composed of native heart matrix and collagen induces cardiac differentiation of human embryonic stem cells without supplemental growth factors.

Our goal was to assess the ability of native heart extracellular matrix (ECM) to direct cardiac differentiation of human embryonic stem cells (hESCs) in vitro. In order to probe the effects of cardiac matrix on hESC differentiation, a series of hydrogels was prepared from decellularized ECM from porcine hearts by mixing ECM and collagen type I at varying ratios. Maturation of cardiac function in embryoid bodies formed from hESCs was documented in terms of spontaneous contractile behavior and the mRNA and protein expression of cardiac markers. Hydrogel with high ECM content (75% ECM, 25% collagen, no supplemental soluble factors) increased the fraction of cells expressing cardiac marker troponin T, when compared with either hydrogel with low ECM content (25% ECM, 75% collagen, no supplemental soluble factors) or collagen hydrogel (100% collagen, with supplemental soluble factors). Furthermore, cardiac maturation was promoted in high-ECM content hydrogels, as evidenced by the striation patterns of cardiac troponin I and by upregulation of Cx43 gene. Consistently, high-ECM content hydrogels improved the contractile function of cardiac cells, as evidenced by increased numbers of contracting cells and increased contraction amplitudes. The ability of native ECM hydrogel to induce cardiac differentiation of hESCs without the addition of soluble factors makes it an attractive biomaterial system for basic studies of cardiac development and potentially for the delivery of therapeutic cells into the heart.

A stimuli-responsive hydrogel for doxorubicin delivery.

The goal of this study was to develop a polymeric carrier for delivery of anti-tumor drugs and sustained release of these agents in order to optimize anti-tumor activity while minimizing systemic effects. We used oligo(poly(ethylene glycol) fumarate) (OPF) hydrogels modified with small negatively charged molecules, sodium methacrylate (SMA), for delivery of doxorubicin (DOX). SMA at different concentrations was incorporated into the OPF hydrogel with a photo-crosslinking method. The resulting hydrogels exhibited sensitivity to the pH and ionic strength of the surrounding environment. Our results revealed that DOX was bound to the negatively charged hydrogel through electrostatic interaction and was released in a timely fashion with an ion-exchange mechanism. Release kinetics of DOX was directly correlated to the concentration of SMA in the hydrogel formulations. Anti-tumor activity of the released DOX was assessed using a human osteosarcoma cell line. Our data revealed that DOX released from the modified, charged hydrogels remained biologically active and had the capability to kill cancer cells. In contrast, control groups of unmodified OPF hydrogels with or without DOX did not exhibit any cytotoxicity. This study demonstrates the feasibility of using SMA-modified OPF hydrogels as a potential carrier for chemotherapeutic drugs for cancer treatments.

Clinical manifestations and prognostic factors in patients with gastrointestinal stromal tumors.

AIM: To investigate the incidence of CD117-positive immunohistochemical staining in previously diagnosed gastrointestinal (GI) tract stromal tumors (GIST) and to analyze the tumors' clinical manifestations and prognostic factors. METHODS: We retrospectively reviewed 91 cases with a previous diagnosis of GI stromal tumor, leiomyoma, or leiomyosarcoma. Tissue samples were assessed with CD117, CD34, SMA and S100 immunohistochemical staining. Clinical and pathological characteristics were analyzed for prognostic factors. RESULTS: CD117 was positive in 81 (89%) of 91 tissue samples. There were 59 cases (72.8%) positive for CD34, 13 (16%) positive for SMA, and 12 (14.8%) positive for S100. There was no gender difference in patients with CD117-positive GIST. Their mean age was 65 years. There were 44 (54%) tumors located in the stomach and 29 (36%) in the small intestine. The most frequent presenting symptoms were abdominal pain and GI bleeding. The mean tumor size was 7.5 +/- 5.7 cm. There were 35 cases (43.2%) with tumors >5 cm. The tumor size correlated significantly with tumor mitotic count and resectability. Tumor size, mitotic count, and resectability correlated significantly with tumor recurrence and survival. There was recurrent disease in 39% of our patients, and their mean survival after recurrence was 16.6 months. Most recurrences were at the primary site or metastatic to the liver. Twenty-six percent of our patients died of their disease. CONCLUSION: Traditional histologic criteria are not specific enough to diagnose GIST. This diagnosis must be confirmed with CD117 immunohistochemical staining. Prognosis is dependent on tumor size, mitotic count, and resectability.