Varying assay geometry to emulate connective tissue planes in an in vitro model of acupuncture needling

Collagen- and hyaluronic acid-based hydrogels and their biomedical applications

Hydrogels have been widely investigated in biomedical fields due to their similar physical and biochemical properties to the extracellular matrix (ECM). Collagen and hyaluronic acid (HA) are the main components of the ECM in many tissues. As a result, hydrogels prepared from collagen and HA hold inherent advantages in mimicking the structure and function of the native ECM. Numerous studies have focused on the development of collagen and HA hydrogels and their biomedical applications. In this extensive review, we provide a summary and analysis of the sources, features, and modifications of collagen and HA. Specifically, we highlight the fabrication, properties, and potential biomedical applications as well as promising commercialization of hydrogels based on these two natural polymers.

Degradation and Remodeling of Epitaxially Grown Collagen Fibrils

INTRODUCTION—

The extracellular matrix (ECM) in the tumor microenvironment contains high densities of collagen that are highly aligned, resulting in directional migration called contact guidance that facilitates efficient migration out of the tumor. Cancer cells can remodel the ECM through traction force controlled by myosin contractility or proteolytic activity controlled by matrix metalloproteinase (MMP) activity, leading to either enhanced or diminished contact guidance.

METHODS—

Recently, we have leveraged the ability of mica to epitaxially grow aligned collagen fibrils in order to assess contact guidance. In this article, we probe the mechanisms of remodeling of aligned collagen fibrils on mica by breast cancer cells.

RESULTS—

We show that cells that contact guide with high fidelity (MDA-MB-231 cells) exert more force on the underlying collagen fibrils than do cells that contact guide with low fidelity (MTLn3 cells). These high traction cells (MDA-MB-231 cells) remodel collagen fibrils over hours, pulling so hard that the collagen fibrils detach from the surface, effectively delaminating the entire contact guidance cue. Myosin or MMP inhibition decreases this effect. Interestingly, blocking MMP appears to increase the alignment of cells on these substrates, potentially allowing the alignment through myosin contractility to be uninhibited. Finally, amplification or dampening of contact guidance with respect to a particular collagen fibril organization is seen under different conditions.

CONCLUSIONS—

Both myosin II contractility and MMP activity allow MDA-MB-231 cells to remodel and eventually destroy epitaxially grown aligned collagen fibrils.

Contact guidance diversity in rotationally aligned collagen matrices

Cancer cell metastasis is responsible for approximately 90% of deaths related to cancer. The migration of cancer cells away from the primary tumor and into healthy tissue is driven in part by contact guidance, or directed migration in response to aligned extracellular matrix. While contact guidance has been a focus of many studies, much of this research has explored environments that present 2D contact guidance structures. Contact guidance environments in 3D more closely resemble in vivo conditions and model cell-ECM interactions better than 2D environments. While most cells engage in directed migration on potent 2D contact guidance cues, there is diversity in response to contact guidance cues based on whether the cell migrates with a mesenchymal or amoeboid migration mode. In this paper, rotational alignment of collagen gels was used to study the differences in contact guidance between MDA-MB-231 (mesenchymal) and MTLn3 (amoeboid) cells. MDA-MB-231 cells migrate with high directional fidelity in aligned collagen gels, while MTLn3 cells show no directional migration. The collagen stiffness was increased through glycation, resulting in decreased MDA-MB-231 directionality in aligned collagen gels. Interestingly, partial inhibition of cell contractility dramatically decreased directionality in MDA-MB-231 cells. The directionality of MDA-MB-231 cells was most sensitive to ROCK inhibition, but unlike in 2D contact guidance environments, cell directionality and speed are more tightly coupled. Modulation of the contractile apparatus appears to more potently affect contact guidance than modulation of extracellular mechanical properties of the contact guidance cue.

STATEMENT OF SIGNIFICANCE

Collagen fiber alignment in the tumor microenvironment directs migration, a process called contact guidance, enhancing the efficiency of cancer invasion and metastasis. 3D systems that assess contact guidance by locally orienting collagen fiber alignment are lacking. Furthermore, cell type differences and the role of extracellular matrix stiffness in tuning contact guidance fidelity are not well characterized. In this paper rotational alignment of collagen fibers is used as a 3D contact guidance cue to illuminate cell type differences and the role of extracellular matrix stiffness in guiding cell migration along aligned fibers of collagen. This local alignment offers a simple approach by which to couple collagen alignment with gradients in other directional cues in devices such as microfluidic chambers.

Acupuncture in the treatment of cancer-related psychological symptoms

Acupuncture is being adopted by cancer patients for a wide range of cancer-related symptoms including highly prevalent psychological symptoms like depression, anxiety, insomnia, and impairment in quality of life. Pharmacological treatment of prevalent symptoms like anxiety, depression, and sleep disturbance can contribute to the high chemical burden already carried by cancer patients, creating additional side effects. As a result, patients and providers alike are interested in evidence-based nonpharmacologic alternatives like acupuncture for these symptoms. This article reviews the current literature (January 2000 through April 2013) for acupuncture in cancer-related psychological symptoms with attention to both efficacy and acupuncture-specific methodology. All published studies that met our review criteria demonstrate a positive signal for acupuncture for the treatment of depression, anxiety, sleep disturbance, and for improving quality of life with most results showing statistical significance. However, there are only a handful of acupuncture studies that were specifically designed to evaluate depression, sleep disturbance, and quality of life as primary outcomes, and no studies were found that looked at anxiety as a primary outcome in this population. Published studies in cancer patients and survivors show that acupuncture treatment is not only safe but also more acceptable with fewer side effects than standard of care pharmacological treatments like antidepressants. Finally, there is wide variability in both the implementation and reporting of acupuncture methods in the literature, with only 2 of 12 studies reporting full details of acupuncture methods as outlined in the revised Standards for Reporting Interventions in Clinical Trials of Acupuncture guidelines, published in 2010 and providing an essential framework for the reporting of acupuncture methodology. This lack of methodological detail affects outcomes, generalizability, and validity of research involving acupuncture. Reasons for ongoing challenges in the development of high-quality acupuncture trials are discussed. In conclusion, results are encouraging for the development of randomized trials to directly evaluate the therapeutic impact of acupuncture in cancer-related psychological symptoms, including depression, anxiety, sleep disturbance, and quality of life, but attention to acupuncture methodological specific challenges in the development of high-quality research is necessary.

Connective tissue fibroblast response to acupuncture: dose-dependent effect of bidirectional needle rotation

BACKGROUND

Although acupuncture-needle manipulation is an important component of acupuncture therapy, little information is currently available on whether or not specific types of needle manipulation produce different effects on the body. Bidirectional (back-and-forth) rotation is one of the most common forms of needle manipulation used in acupuncture practice.

OBJECTIVES

In this study, we hypothesized that bidirectional acupuncture needle rotation causes dose-dependent active cytoskeletal remodeling in connective tissue fibroblasts similar to that previously demonstrated with unidirectional rotation.

INTERVENTIONS

Subcutaneous tissue explants from 18 mice were randomized to varying amounts of bidirectional rotation cycles (8-64) and rotation-cycle amplitude (180 degrees -720 degrees ) ex vivo for 30 minutes, followed by tissue fixation, confocal microscopy, and measurement of fibroblast cell body cross-sectional area.

RESULTS

As with unidirectional rotation, fibroblasts responded to bidirectional rotation with extensive cell spreading and lamellipodia formation. Bidirectional needle rotation had a significant overall effect on fibroblast cell body cross sectional area (analysis of variance, p < 0.001). The cellular response to bidirectional rotation was nonmonotonic with maximal responses occurring within specific stimulus windows with regard to cycle amplitude and cycle number.

CONCLUSIONS

These findings demonstrate that subtle differences in acupuncture-needle manipulation techniques can affect cellular responses in mouse subcutaneous connective tissue. Further studies will be needed to determine whether these connective-tissue responses are related to therapeutic effects.