**Abstract**

A recent survey of practicing plastic surgeons showed that regenerative medicine is the current top interest of esthetic consumers worldwide. Patients are frequently requesting correction of small regions, instead of opting for an all-encompassing procedure associated with prolonged recovery time. Thus, the field of "microlifting" has emerged. This is a new approach in which minimally invasive procedures can be utilized to accomplish outcomes formerly reserved for traditional surgery. The combination of polydioxanone (PDO) threads and topical exosomes is a method of treating both underlying soft tissue laxity and the surface of aging skin. The application of exosomes can deliver topical growth factors and targeted peptides to assist in rapid skin surface healing. More than a simple delivery vesicle, exosomes communicate with cells at the recipient site and can induce cellular change. PDO threads can be used subcutaneously as both a suspension device and regenerative biostimulatory device. Usually resorbed at 6 months post-insertion, these threads leave behind a linear network of collagen and elastin fibers that remains long after the polydioxanone is gone. Combination therapies can target several concerns when performed simultaneously. This regenerative method is well accepted by patients due to minimal cost and recovery time.

**Keywords:** injectable implant, threadlift, exosomes, particulate drug delivery, growth factors, PDO threads, filler threads

## **1. Introduction**

The number of practitioners joining the esthetic field is increasing rapidly. These specialists range in background and training from aestheticians, chiropractors, and acupuncturists to dentists, dermatologists, facial plastic, and plastic surgeons. While more patients are seeking treatment for concerns regarding facial and body region challenges, few desire traditional surgical intervention with the associated risk and recovery time. Regional differences dictate the preferences of the clientele, but many do seek the restoration of their own youthful appearance instead of a drastic change. In years past, the emergence of stem cell therapy has been viewed by many as a magic wand that could restore aging tissues to a youthful state without surgical intervention. Some limitations to treatment with mesenchymal stem cells (MSCs) include a low survival rate, tumorigenicity, poor "take," and lack of efficacy [1]. It is thought that many of the supposed effects of mesenchymal stem cells are indeed paracrine effects,

mediated by acellular factors that are transmitted with the cells, but not by direct effects of the cells themselves [2]. For several years, filler companies have focused on biostimulatory effects seen after the hyaluronic acid, hydroxyapatite, or other fillers have been metabolized [3, 4]. The injectable poly-L-lactic acid works on this principle. A problem can occur when so much filler has been injected that the response turns from collagen stimulation to fibrosis. Some long-term injectable patients note a "woody" or stiff feeling, difficulty achieving a natural animated expression, and chronic swelling in a treatment region years after the original product was injected. A preferred solution would be induction of an existing tissue response using regenerative options now available and in development. Restoration of dermal thickness, collagen, and elastin and self-repair of the adipose framework upon which the skin rests are concepts that make sense to our esthetic customer base.
