Stem cell-derived tissue-engineered constructs for hemilaryngeal reconstruction

OBJECTIVES: As an initial step toward our goal of developing a completely tissue-engineered larynx, the aim of this study was to describe and compare three strategies of creating tissue-engineered muscle-polymer constructs for hemilaryngeal reconstruction. METHODS: Cartilage-mimicking polymer was developed from electrospun poly(D,L-lactide-co-ε-caprolactone) (PCL). Primary muscle progenitor cell cultures were derived from syngeneic F344 rat skeletal muscle biopsies. Twenty F344 rats underwent resection of the outer hemilaryngeal cartilage with the underlying laryngeal adductor muscle. The defects were repaired with muscle stem cell-derived muscle-PCL constructs (5 animals), myotube-derived muscle-PCL constructs (5 animals), motor end plate-expressing muscle-PCL constructs (5 animals), or PCL alone (controls; 5 animals). The outcome measures at 1 month included animal survival, muscle thickness, and innervation status as determined by electromyography and immunohistochemistry. RESULTS: All of the animals survived the 1-month implant period and had appropriate weight gain. The group that received motor end plate-expressing muscle-PCL constructs demonstrated the greatest muscle thickness and the strongest innervation, according to electromyographic activity and the percentage of motor end plates that had nerve contact. CONCLUSIONS: Although all of the tissue-engineered constructs provided effective reconstruction, those that expressed motor end plates before implantation yielded muscle that was more strongly innervated and viable. This finding suggests that this novel approach may be useful in the development of a tissue-engineered laryngeal replacement

The Pairing of Trigger Point Dry Needling with Rehabilitation Techniques

Trigger point dry needling is a manual treatment modality used for individuals experiencing tightness, pain, and inhibited range of motion in any region of the body. Dry needling can be described as the insertion of a blunt, microfilament non-medicated needle into the skin for the purpose of targeting specific muscles, which contain tight bands known as trigger points. When the needle is inserted into the trigger point the muscle contracts, holds tight to the needle, and elicits a neural twitch response. This ultimately causes the muscle to relax, allowing for reduction in pain and improvements in range of motion. Although the use of dry needling is rising in popularity in the United States, knowledge of its use and effects is limited. Fortunately, more research is being conducted on this form of treatment. In this thesis, the purpose and physiological effects of dry needling will be discussed in detail, along with a comparison between other alternate medical modalities of treatment which target trigger points. In addition, current research on the effectiveness of incorporating dry needling with other manual therapeutic modalities will be discussed. Dry needling has been shown to be very effective in treating trigger points by improving range of motion, decreasing pain, reducing muscle tightness, and increasing muscle oxygenation. Positive effects of dry needling are even more likely to occur when paired with other modes of therapeutic treatment, often in a physical therapy setting but may also be performed by other health professionals including chiropractors, athletic trainers, occupational therapists, and physicians

A silver impregnation method for motor and sensory nerves and their endings in formalin-fixed mammalian muscles

A silver impregnation method is described which shows motor and sensory nerves and their endings in formalin-fixed mammalian muscles. The method works with the same reliability on flattened muscle pieces as well as on frozen sections. Large nerve bundles, myelinated and non-myelinated single axons, and terminals impregnated by this method stand out black against a light brown background

Dermatology

Dermatology continues to develop at a steady pace. In the past few years there have been exciting advances in our understanding of skin structure and function in health and disease and progress in genetics, epidemiology, immunology, pharmacology and clinical dermatology that have led to new approaches for managing skin diseases. This article will discuss a number of recent advances including treatments that have entered clinical practice recently or are likely to do so soon and have an impact on dermatological practice in years to come. Issues likely to be of interest to a general medical audience are emphasised.peer-reviewe

BDNF is a mediator of glycolytic fiber-type specification in mouse skeletal muscle

Brain-derived neurotrophic factor (BDNF) influences the differentiation, plasticity, and survival of central neurons and likewise, affects the development of the neuromuscular system. Besides its neuronal origin, BDNF is also a member of the myokine family. However, the role of skeletal muscle-derived BDNF in regulating neuromuscular physiology in vivo remains unclear. Using gain- and loss-of-function animal models, we show that muscle-specific ablation of BDNF shifts the proportion of muscle fibers from type IIB to IIX, concomitant with elevated slow muscle-type gene expression. Furthermore, BDNF deletion reduces motor end plate volume without affecting neuromuscular junction (NMJ) integrity. These morphological changes are associated with slow muscle function and a greater resistance to contraction-induced fatigue. Conversely, BDNF overexpression promotes a fast muscle-type gene program and elevates glycolytic fiber number. These findings indicate that BDNF is required for fiber-type specification and provide insights into its potential modulation as a therapeutic target in muscle diseases