Pericytes in sarcomas of bone

The Therapeutic Potential of Pericytes in Bone Tissue Regeneration

Pericytes, as perivascular cells, are present in all vascularized organs and tissues, and they actively interact with endothelial cells in capillaries and microvessels. Their involvement includes functions like blood pressure regulation, tissue regeneration, and scarring. Studies have confirmed that pericytes play a crucial role in bone tissue regeneration through direct osteodifferentiation processes, paracrine actions, and vascularization. Recent preclinical and clinical experiments have shown that combining perivascular cells with osteogenic factors and tissue-engineered scaffolds can be therapeutically effective in restoring bone defects. This approach holds promise for addressing bone-related medical conditions. In this review, we have emphasized the characteristics of pericytes and their involvement in angiogenesis and osteogenesis. Furthermore, we have explored recent advancements in the use of pericytes in preclinical and clinical investigations, indicating their potential as a therapeutic resource in clinical applications.

The interaction between osteosarcoma and other cells in the bone microenvironment: From mechanism to clinical applications

Osteosarcoma is a primary bone tumor with a high mortality rate. The event-free survival rate has not improved significantly in the past 30 years, which brings a heavy burden to patients and society. The high heterogeneity of osteosarcoma leads to the lack of specific targets and poor therapeutic effect. Tumor microenvironment is the focus of current research, and osteosarcoma is closely related to bone microenvironment. Many soluble factors and extracellular matrix secreted by many cells in the bone microenvironment have been shown to affect the occurrence, proliferation, invasion and metastasis of osteosarcoma through a variety of signaling pathways. Therefore, targeting other cells in the bone microenvironment may improve the prognosis of osteosarcoma. The mechanism by which osteosarcoma interacts with other cells in the bone microenvironment has been extensively investigated, but currently developed drugs targeting the bone microenvironment have poor efficacy. Therefore, we review the regulatory effects of major cells and physical and chemical properties in the bone microenvironment on osteosarcoma, focusing on their complex interactions, potential therapeutic strategies and clinical applications, to deepen our understanding of osteosarcoma and the bone microenvironment and provide reference for future treatment. Targeting other cells in the bone microenvironment may provide potential targets for the development of clinical drugs for osteosarcoma and may improve the prognosis of osteosarcoma.

Comparison of Sample Preparation Methods for Rare Cell Isolation in Microfluidic Devices

The analysis of circulating tumor cells (CTCs) is important for cancer diagnosis and prognosis. Microfluidics has been employed for CTC analysis due to their scaling advantages and high performance. However, pre-analytical methods for CTC sample preparation are often combined with microfluidic platforms because a large sample volume is required to detect extremely rare CTCs. Among pre-analytical methods, Ficoll-Paque™, OncoQuick™, and RosetteSep™ are commonly used to separate blood cells of interest. To compare their performance, we spiked L3.6pl pancreatic cancer cells into healthy blood samples, then employed each technique to prepare blood samples, followed by using a microfluidic platform to capture and detect L3.6pl cells. We found these three methods have similar performance, though the slight edge of RosetteSep™ over Ficoll-Paque™ is statistically significant. We also studied the effects of the tumor cell concentrations on the performance of the frequently used Ficoll-Paque™ method. Furthermore, we examined the repeatability and variability of each pre-analytical technique and the microfluidics-enabled detection. This study will provide researchers and clinicians with comparative data that can influence the choice of sample preparation method, help estimate CTC loss in each pre-analytical method, and correlate the results of clinical studies that employ different techniques.

Exercise Inhibits Doxorubicin-Induced Damage to Cardiac Vessels and Activation of Hippo/YAP-Mediated Apoptosis

Dose-related cardiomyopathy is a major side effect following doxorubicin (Dox). To investigate whether exercise (Ex)-induced vasculogenesis plays a role in reducing Dox-induced cardiotoxicity, GFP⁺ bone marrow (BM) cells from GFP transgenic mice were transplanted into wild-type mice. Transplanted mice were treated with Dox, Ex, Dox+Ex, or control. We found Dox therapy resulted in decreased systolic and diastolic blood flow, decreased ejection fraction and fractional shortening, and decreased vascular endothelial cells and pericytes. These abnormalities were not seen in Dox+Ex hearts. Heart tissues from control-, Ex-, or Dox-treated mice showed a small number of GFP⁺ cells. By contrast, the Dox+Ex-treated hearts had a significant increase in GFP⁺ cells. Further analyses demonstrated these GFP⁺ BM cells had differentiated into vascular endothelial cells (GFP⁺CD31⁺) and pericytes (GFP⁺NG2⁺). Decreased cardiomyocytes were also seen in Dox-treated but not Dox+Ex-treated hearts. Ex induced an increase in GFP⁺c-Kit⁺ cells. However, these c-Kit⁺ BM stem cells had not differentiated into cardiomyocytes. Dox therapy induced phosphorylation of MST1/2, LATS1, and YAP; a decrease in total YAP; and cleavage of caspase-3 and PARP in the heart tissues. Dox+Ex prevented these effects. Our data demonstrated Dox-induced cardiotoxicity is mediated by vascular damage resulting in decreased cardiac blood flow and through activation of Hippo-YAP signaling resulting in cardiomyocyte apoptosis. Furthermore, Ex inhibited these effects by promoting migration of BM stem cells into the heart to repair the cardiac vessels damaged by Dox and through inhibiting Dox-induced Hippo-YAP signaling-mediated apoptosis. These data support the concept of using exercise as an intervention to decrease Dox-induced cardiotoxicity.

Neuronal Repressor REST Controls Ewing Sarcoma Growth and Metastasis by Affecting Vascular Pericyte Coverage and Vessel Perfusion

Survival rates for Ewing sarcoma (ES) patients with metastatic disease have not improved in over 20 years. Tumor growth and metastasis are dependent on tumor vasculature expansion; therefore, identifying the regulators that control this process in ES may provide new therapeutic opportunities. ES expresses high levels of repressor element 1 silencing transcription factor (REST), which is regulated by the EWS-FLI-1 fusion gene. However, the role of REST in ES growth and the regulation of the tumor vasculature have not been elucidated. To study this role, we established REST-knockout human TC71 ES cell lines through CRISPR/Cas9 recombination. While knockout of REST did not alter tumor cell proliferation in vitro, REST knockout reduced tumor growth and metastasis to the lung in vivo and altered tumor vascular morphology and function. Tumor vessels in the REST-knockout tumors had a punctate appearance with significantly decreased tumor vascular pericytes, decreased perfusion, and increased permeability. REST-knockout tumors also showed increased apoptosis and hypoxia. These results indicate that REST plays a critical role in ES vascular function, which in turn impacts the ability of ES tumors to grow and metastasize. These findings therefore provide a basis for the targeting of REST as a novel therapeutic approach in ES.

Carcinoma and Sarcoma Microenvironment at a Glance: Where We Are

Cells and extracellular matrix (ECM) components represent the multifaceted and dynamic environment that distinguishes each organ. Cancer is characterized by the dysregulation of the composition and structure of the tissues, giving rise to the tumor milieu. In this review, we focus on the microenvironmental analysis of colorectal cancer (CRC) and rhabdomyosarcoma (RMS), two different solid tumors. While a lot is known about CRC environment, for RMS, this aspect is mostly unexplored. Following the example of the more complete CRC microenvironmental characterization, we collected and organized data on RMS for a better awareness of how tissue remodeling affects disease progression.