Tissue engineering and regeneration
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
Tissue engineering and regenerative medicine are relatively new but rapidly expanding multidisciplinary fields of clinical medicine, which have the potential to revolutionise the treatment of a wide range of human diseases. The ability of tissues to undergo spontaneous repair and regeneration is highly variable but in many cases very limited. Bone, for example, is one of the few tissues able to undergo effective regeneration, so long as the defective tissue is not too extensive. Adjacent cartilage, on the other hand, in common with most tissues, has little or no propensity for spontaneous regeneration, in terms of quality and quantity, following injury or arthritic disease. The limited ability of tissues to repair themselves has driven the desire to develop cell therapy and tissue engineering approaches to repair or replace diseased and damaged tissues. In most cases this involves the implantation of cells and tissues that have been expanded in vitro (outside the body), either as a cell therapy or with cells seeded into natural or synthetically based tissue scaffolds. However, cells (with or without expansion) and cellularised or cell-free scaffolds may also be implanted into areas of tissue injury with the aim of promoting in vivo (inside the body) regeneration and repair of tissues. This chapter provides a brief overview of tissue engineering and regenerative therapy, highlighting the opportunities, challenges and likely future directions.
Endothelins in Inflammation
Sami I. Said in Proinflammatory and Antiinflammatory Peptides, 2020
A major aspect of tissue repair during an inflammatory response is that cells are stimulated to change from a quiescent phenotype to a synthetic dividing one. In the process of atherosclerosis, the phenotype transition of vascular smooth muscle cells is controlled by various cytokines released from macrophages or endothelial cells, such as IL-1, TNF-α, and TGF (207). In this context, it has been observed that IL-1 dramatically inhibits ET-1-induced DNA synthesis and proliferation of human cultured aortic smooth muscle, whereas IL-8, TNF-α, and TGF are ineffective (213). It appears plausible to anticipate that similar interactions between ETs, cytokines, and growth factors possibly occur with regard to proliferation, migration, and differentiation of other cell types during inflammation.
Acupuncture
W. John Diamond in The Clinical Practice of Complementary, Alternative, and Western Medicine, 2017
Lerner and Kirsch compared microcurrent stimulation to placebo treatment and found 37% greater short-term relief and 75% longer-term relief from the microcurrents. [ACA Journal of Chiropractic, November 1981]. Cheng et al. showed that microcurrents increased tissue ATP levels threefold to fivefold, and enhanced the cellular membrane transport mechanism and protein synthesis by 30% to 40%. Both factors are critical to tissue repair and healing. [Clinical Orthopedics and Related Research, #171 Nov.-Dec.,1982]. Cheng et al. also determined that currents exceeding 1000 microamps (one milliamp or above) actually inhibited protein synthesis, as well as amino acid transport, by as much as 50%. Also, electrolysis, the breakdown of the needle metal as well as the surrounding tissue, becomes more evident with milliamperage currents.55
Wound dressings as growth factor delivery platforms for chronic wound healing
Published in Expert Opinion on Drug Delivery, 2021
Ovidio Catanzano, Fabiana Quaglia, Joshua S. Boateng
As the outermost barrier of the body, the skin is the organ most challenged by a range of external stress factors (physical, chemical, thermal or radiation), resulting in frequent tissue damage. Every animal specie can regenerate their tissue after injury, but not all organisms regenerate in the same way. Fish and amphibians, such as zebrafish and salamanders, can perfectly regenerate complex tissues without scar formation, and this happens even in cases of extensive damage such as the loss of their limbs[1]. Higher animals, such as mammals, are generally incapable of complete tissue regeneration and have developed a complex response to injury, which is characterized by four stages (i.e., hemostasis, inflammation, proliferation, and remodeling) to restore the integrity of damaged tissue [2]. In humans, perfect tissue regeneration has only been described in fetal skin [3]. In adults however, tissue repair commences immediately following tissue injury and, with few exceptions, results in the formation of an acellular fibrotic matrix (i.e., scar tissue) [4]. The replacement of functional tissue with fibrous connective tissue leads to a loss of original tissue structure and function, which alters the microarchitecture of the whole organ, eventually resulting in failure [5,6]. Fibrosis is a major pathological feature of many chronic diseases, and it has been estimated that it is associated with 45% of non-accident related casualties in the USA [7].
Cryptotanshinone enhances wound healing in type 2 diabetes with modulatory effects on inflammation, angiogenesis and extracellular matrix remodelling
Published in Pharmaceutical Biology, 2020
Min Song, Lu Chen, Lusha Zhang, Chunxiao Li, Joel Wake Coffie, Zhirui Fang, Liyuan Zhang, Shaoxia Wang, Xiumei Gao, Hong Wang
Diabetes is a metabolic disease associated with a large number of vascular complications including inability of wounds to heal (Okonkwo and DiPietro 2017). The prevalence of diabetes is widespread and has been growing in epidemic proportions. Currently, the disease affects 422 million adults worldwide according to the report of the World Health Organization (WHO) (Zubair and Ahmad 2019), but is expected to reach 693 million by 2045 (Cho et al. 2018). Approximately, 1% of diabetic patients per year require lower-limb amputations, which is a major cause of non-traumatic amputation (Rice et al. 2014). Normal wound repair is a series of coordination of intricate and orderly biological and molecular events, consisting of several overlapping stages: inflammation, new tissue formation, re-epithelialization, matrix deposition and remodelling (Qi et al. 2015; Feng et al. 2019). However, diabetic pathological circumstances lead to excessive inflammatory response and dysfunction of endotheliocytes (Liang et al. 2014; Abd El-Khalik et al. 2020). Concomitantly, processes of new tissue formation and re-epithelialization are disrupted, successful tissue repair fail to proceed and wound healing is delayed (Chin et al. 2019).
Chronic diseases and allergies are risk factors predictive of a history of Medial Tibial Stress Syndrome (MTSS) in distance runners: SAFER study XXIV
Published in The Physician and Sportsmedicine, 2023
Pieter-Henk Boer, Martin P. Schwellnus, Esmè Jordaan
The second main finding from our study was that a history of allergies was an independent risk factor predictive of a history of MTSS. This finding is similar to what we recently reported for any gradual onset injury in trail runners [23] and distance runners [24]. Again, we cannot show cause-effect, but there are also possible biological mechanisms linking chronic allergies to gradual onset soft tissue and bony injuries. Allergies are characterized by chronic inflammation, and there are epidemiological data in adults and children linking allergies to low bone mineral density and osteoporosis [46,47]. Common medications to treat allergies are corticosteroids and histamine receptor antagonists (antihistamines). Corticosteroids have been associated with the development of myopathy and osteopenia [38,48]. In a recent review, it was concluded that chronic blockade of histamine H1/H2 receptors can lead to impairment of microvascular and mitochondrial adaptations to interval training in humans [49]. Although speculative, this may affect tissue repair following injury. It is clear that the association between chronic diseases and/or allergies and gradual onset injuries such as a history of MTSS require further investigation. However, these associations may be very important for clinicians treating patients with MTSS because it may influence, for example, the rate at which healing may take place following repetitive injury in subgroups of higher risk individuals such as those with chronic diseases or allergies.