Fat Removal

Invasive and Non-invasive Body Contouring

Mathew Avram, Mathew Avram

• Editorial: Wiley-Blackwell
• Año: 2015
• ISBN:
  9781118661956
• Edición: 1
• Categoría: Medizin
• Categoría: Dermatologie

The perception of an inadequate body shape is a cause of concern to many people, and new techniques for altering body shape are increasingly being developed and offered to patients. Of these, the removal and transfer of fat is fast growing in importance and availability. This practical guide offers a comprehensive overview of this rapidly-evolving field, and thorough coverage of the implementation of fat removal techniques, both invasive and non-invasive, in a cosmetic practice.

It begins with an overview of basic fat anatomy and physiology as an important introduction to this topic. The distinction between the physiology and treatment of cellulite and fat is also discussed. The next section of the book covers invasive treatments of fat such as traditional liposuction, laser-assisted liposuction, fat transfer procedures and mesotherapy. The latter half of the book largely focuses on non-invasive treatments for fat, including radiofrequency, ultrasound, cooling and laser technologies for fat removal. Throughout, potential complications and pitfalls of the various treatments are discussed.

Edited by Matthew Avram, with contributions from a group of clinical stars, this book will appeal to cosmetic dermatologists, plastic surgeons, aesthetic medical practitioners, and obstetricians/gynaecologists

Chapter 1
Introduction

Hrak Ray Jalian¹, Alison Avram² and Mathew M. Avram²

¹ David Geffen School of Medicine, University of California Los Angeles (UCLA), CA, USA

² Department of Dermatology, Massachusetts General Hospital, Boston, MA

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1. Anatomy and physiology of adipose tissue
2. Adipogenesis: from stem cell to fat cell
3. Summary
4. References

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Fat is a ubiquitous component of the skin and subcutaneous tissues. In the past, many in medicine largely viewed fat as a receptacle for the passive storage of energy: a savings account of nutrients when metabolic expenditure exceeds caloric intake. However, as we pool the knowledge of fat across different specialties of medicine, we are beginning to understand the complex physiology of fat in both normal and disease states.

Dysregulation of adipose tissue, whether it be in excess in conditions such as obesity, or diminished such as in lipoatrophy, has clearly demonstrated that fat has complex metabolic, endocrine, hormonal, and immune functions (Figure 1.1). Obesity is a rising epidemic in the United States with upwards of 1 in 3 Americans being obese [1]. It has been linked to numerous chronic illnesses such as non-insulin- dependent diabetes, heart disease, liver disease, arthritis, as well as certain types of cancer [2–5].

Figure 1.1 Key functions of adipocytes. Adipocytes play important roles in lipid and glucose metabolism storing them as TG. In times of energy need, these TGs are metabolized to FFA and glycerol and released into the circulation. In addition to its metabolic role, lipids, hormones, peptides, and cytokines have important endocrine roles on downstream tissue. AGT, angiotensinogen; FFA, free fatty acid; IL-6, interleukin-6; PAI-1, plasminogen activator inhibitor type 1; TG, triacylglycerol; TNF-α, tumor necrosis factor alpha.

In addition to the health consequences, these conditions often change fat distribution patterns, affecting the appearance of patients. Fat distribution has evolved to become a large component of cosmetic and procedural dermatology. In fact, as we age, cosmetic concerns regarding fat, either focal accumulation or atrophy, have become a large proportion of cosmetic consultations in physicians' offices. Currently, liposuction is one of the most common cosmetic procedures performed in the United States. Additionally, new non-invasive technologies that can successfully improve focal adiposity in the office without pain medication or sedation are becoming increasingly popular. On the other end of the spectrum, selective loss of fat, lipoatrophy, is also an emerging problem as our knowledge of facial aesthetics evolves. Focal facial volume loss can now be adequately treated with soft tissue augmentation and volumetric filling. Various dermal fillers have received clearance from the U.S. Food and Drug Administration (FDA) over the last decade and the number of these procedures has nearly doubled in this same time frame [6].

In order to successfully and safely perform cosmetic procedures involving the manipulation of fat, it is essential to understand the complex physiology and intricate interplay of fat as it relates to human health. Thus, it is important to gain a basic knowledge of adipogenesis, anatomy, and the physiology of fat. This chapter will serve as an abbreviated introduction to normal adipose tissue anatomy and physiology with emphasis placed on adipogenesis, the hormonal and endocrine functions of fat, and differences in adipose tissue types. This is in no way an exhaustive review, as adipose tissue is a complex organ with a multiplicity of functions, but will rather be focused on fundamental concepts that may aid in defining better treatments for conditions that are relevant to our practices.

Anatomy and physiology of adipose tissue

Fat is composed of cells known as adipocytes, the fundamental unit of fat. These cells have manifold effects on the body including energy expenditure, temperature homeostasis, and innate and adaptive immunity. Taken together, adipocytes are organized and distributed as a multi-depot organ known as adipose tissue [7]. Adipose tissue is more than just “fat” tissue. It should be thought of as a complex organ with a variety of important metabolic functions. In fact, it is composed of mature adipocytes, blood vessels, nerves, fibroblasts, and adipocyte precursor cells known as preadipocytes. Among mature adipocytes, two cytotypes can be distinguished by differences in their color and function. White adipocyte tissue (WAT) is composed of white adipocytes and macroscopically has an ivory or yellow appearance. Brown adipocyte tissue (BAT) appears brown and is composed predominantly of brown adipocytes. These two types of adipocyte tissue differ in their distribution and physiological function. Both WAT and BAT receive a vascular and nerve supply. Compared with WAT, BAT has as an abundance of mitochondria and a richer vascular tree accounts for its “brown” appearance [8]. WAT is far more abundant than BAT.

White and brown adipocytes are histologically distinct differing in size and distribution of lipid droplets and organelles [9]. White adipocytes are spherical in shape and have a single, unilocular lipid droplet occupying the cytoplasm with a relatively small eccentric nuclei rimming the periphery [10]. Brown adipocytes, in contrast, are polygonal cells with multiple smaller, “multilocular” lipid droplets, centrally placed nuclei, and a high mitochondrial content [11–13]. WAT and BAT also differ in their distribution and function. WAT is distributed in depots in two main anatomic subdivisions: intra-abdominal visceral fat and subcutaneous fat. The subcutaneous fat is further divided into superficial and deep subcutaneous tissue [14]. BAT can be found in characteristic locations in neonates including the interscapular region, neck, axilla, and around the great vessels.

White adipose tissue

The function of WAT can be largely grouped into three main categories: (i) lipid metabolism, (ii) glucose metabolism, and (iii) endocrine functions. This is a somewhat simplified break-down of the function of WAT as these functions are all intertwined and closely regulated by the same factors. Storage of energy in the form of lipids is key to the function and existence of our species. Without the ability to efficiently store energy, caloric intake from the environment would need to be continuous. Energy storage in adipose tissue allows for humans to break down nutrients in order to have a constant supply of energy between meals or even during periods of prolonged starvation. In times of energy excess, digested free fatty acids (FFA) get stored as triacylglycerides (TGs) in adipocytes [15]. TGs are high-density energy units efficiently packed within adipocytes. In times of nutritional need, TGs are broken down into FFA and glycerol, a process known as lipolysis. In turn, FFA can be oxidized through various metabolic pathways to produce adenosine triphosphate (ATP), the basic energy unit of metabolism [16]. Lipid metabolism serves as a balance between TG synthesis, fatty acid uptake, and TG hydrolysis. Multiple hormones influence the balance between catabolism versus anabolism of lipids including insulin, cortisol, testosterone, and growth hormone. Their interactions are tightly regulated and highly complex and are beyond the pur...