Total Breast Reconstruction with Fat Grafting Combined with Internal Tissue Expansion

Physical Expansion Preconditioning Promotes Host-Derived Adipocyte Dedifferentiation and Migration into Fat Grafts in a Murine Model

BACKGROUND

The unstable recipient conditions after fat grafting remain an obstacle for tissue volumization. The interaction between fat grafts and recipient sites is not fully understood. The authors hypothesize that recipient-derived adipocytes undergo dedifferentiation and migrate into fat grafts in tissue regeneration.

METHODS

To observe the participation from recipient fat pad, the authors established a recipient adipocyte-tracing model where 0.2 mL of inguinal fat from 10 8-week-old C57BL/6 mice was grafted to 10 tamoxifen-treated AdipoqCre;mT/mG mice. Next, to evaluate the impact of physical force on recipient fat and fat graft, a murine internal expansion model was established by implanting a 1-mL internal expander on the inguinal fat pad of the lineage tracing mice that received fat graft from C57BL/6 mice. Transplanted adipose tissue was collected and analyzed by immunostaining of green fluorescent protein (GFP), tdTomato, perilipin, and CD31.

RESULTS

In the observing model, immunostaining revealed that both GFP+ and tdTomato + cells from the recipient fat pad presented in fat grafts. Among the GFP + cells, most of them were perilipin + adipocytes and other perilipin - cells co-expressed octamer-binding transcription factor 4, indicating dedifferentiated adipocytes. In the internal expansion model, internal expansion increased GFP + cells in fat graft. Both octamer-binding transcription factor 4-positive/GFP + (0.23 ± 0.01 versus 0.12 ± 0.04) and perilipin + /GFP + (0.17 ± 0.02 versus 0.06 ± 0.01) cells were increased in the expanded group, compared with control.

CONCLUSIONS

Host-derived adipocytes participate in fat graft regeneration through migration and dedifferentiation, which could be enhanced by internal expansion to increase fat graft retention rate. Further study using a larger animal model is needed, because this is a murine study.

CLINICAL RELEVANCE STATEMENT

Surgeons are encouraged to use physical expansion preconditioning of the recipient site. Subsequent and multiple fat grafting into the fat layer is encouraged to obtain satisfactory soft-tissue volumization.

Preconditioning Strategies for Improving the Outcome of Fat Grafting

Autologous fat grafting is a common procedure in plastic, reconstructive, and aesthetic surgery. However, it is frequently associated with an unpredictable resorption rate of the graft depending on the engraftment kinetics. This, in turn, is determined by the interaction of the grafted adipose tissue with the tissue at the recipient site. Accordingly, preconditioning strategies have been developed following the principle of exposing these tissues in the pretransplantation phase to stimuli inducing endogenous protective and regenerative cellular adaptations, such as the upregulation of stress-response genes or the release of cytokines and growth factors. As summarized in the present review, these stimuli include hypoxia, dietary restriction, local mechanical stress, heat, and exposure to fractional carbon dioxide laser. Preclinical studies show that they promote cell viability, adipogenesis, and angiogenesis, while reducing inflammation, fibrosis, and cyst formation, resulting in a higher survival rate and quality of fat grafts in different experimental settings. Hence, preconditioning represents a promising approach to improve the outcome of fat grafting in future clinical practice. For this purpose, it is necessary to establish standardized preconditioning protocols for specific clinical applications that are efficient, safe, and easy to implement into routine procedures.

Internal Expansion Preconditioning of Recipient Site Increases Fat Graft Retention by Enriching Stem Cell Pool and Inducing Browning in Rats

BACKGROUND

Fat grafting has an unsatisfactory retention rate for breast reconstruction because of poor recipient conditions. The contribution of the recipient site to fat grafts is unknown. In this study, the authors hypothesize that tissue expansion could improve fat graft retention by preconditioning the recipient fat pad.

METHODS

Overexpansion was achieved using 10-mL cylindrical soft-tissue expanders implanted beneath the left inguinal fat flaps of 16 Sprague-Dawley rats (weighing 250 to 300 g), whose contralateral parts were implanted with a silicone sheet as a control. After 7 days of expansion, the implants were removed and both inguinal fat flaps received 1 mL of fat grafts from eight donor rats. Fluorescent dye-labeled mesenchymal stromal cells were injected into rats and tracked in vivo by fluorescence imaging. Transplanted adipose tissue was harvested at 4 and 10 weeks ( n = 8 per time point).

RESULTS

After 7 days of expansion, OCT4 + ( P = 0.0002) and Ki67 + ( P = 0.0004) areas were increased with up-regulated expression of CXCL12 in recipient adipose flaps. An increasing number of CM-DiI-positive mesenchymal stromal cells were observed in the expanded fat pad. At 10 weeks after fat grafting, retention rate, measured using the Archimedes principle, was much higher in the expanded group than in the nonexpanded group (0.3019 ± 0.0680 versus 0.1066 ± 0.0402; P = 0.0005). Histologic and transcriptional analyses revealed that angiogenesis was enhanced, and macrophage infiltration was decreased in the expanded group.

CONCLUSION

Internal expansion preconditioning increased circulating stem cells into the recipient fat pad and contributed to improved fat graft retention.

CLINICAL RELEVANCE STATEMENT

Patients who have limited soft tissue after mastectomy are encouraged to undergo fat grafting. Then, an internal expander could be placed beneath the transferred fat. After internal expansion preconditioning of the recipient site, fat grafting could be performed again for soft-tissue volumization.

Fat Grafting following Internal Tissue Expansion: An Option for Breast Reconstruction after Total Mastectomy

Background:

Breast reconstruction is currently performed as standard practice.

Methods:

A prospective study was performed of patients after total mastectomy who underwent autologous breast reconstruction with fat grafting (FG) combined with internal tissue expansion between September 2015 and December 2020. The patients were classified into groups A to F depending on the steps of breast reconstruction. Groups A and B described patients with completed breast reconstruction with FG and expander removal, with or without nipple/areola complex reconstruction. C described patients during deflation of the expander combined with simultaneous FG. D described patients after expander implantation and refilling. E described patients after first FG, and F included patients who discontinued reconstruction with the described method and converted to reconstruction with a breast implant.

Results:

Among 22 treated patients‚ two were after first FG (9.09%‚ group E), two were after expander implantation and refilling (9.09%‚ group D), three were during deflation of the expander combined with simultaneous FG (13.63%‚ group C), and four (18.18%) had completed breast reconstruction—two (9.09%) without NAC reconstruction and symmetrization (group B) and two (9.09%) with completed breast reconstruction (group A). In 11 patients (50%), breast reconstruction was abandoned after expander implantation and one to three FG procedures (group F), converting to breast reconstruction with a breast implant.

Conclusions:

This study demonstrated successful breast reconstruction using FG and expander implantation. Breast reconstruction using this method is safe and enables possible abandonment at any treatment stage, as well as conversion to breast reconstruction with implants.

Surgical Decision Making in Autologous Fat Grafting: An Evidence-Based Review of Techniques to Maximize Fat Survival

Autologous fat grafting is an important tool in plastic surgery and is widely used for a variety of applications, both aesthetic and reconstructive. Despite an ever-increasing list of indications and extensive research over many years into improving outcomes, fat grafting remains plagued by incomplete and often unpredictable graft survival. Decisions made at each stage of surgery can potentially contribute to ultimate success, including donor site selection and preparation, fat harvest, processing, and purification of lipoaspirate, recipient site preparation, and delivery of harvested fat to the recipient site. In this review, we examine the evidence for and against proposed techniques at each stage of fat grafting. Areas of consensus identified include use of larger harvesting and grafting cannulas and slow injection speeds to limit cell damage due to shearing forces, grafting techniques emphasizing dispersion of fat throughout the tissue with avoidance of graft pooling, and minimizing exposure of the lipoaspirate to the environment during processing. Safety considerations include use of blunt-tipped needles or cannulas to avoid inadvertent intravascular injection as well as awareness of cannula position and avoidance of danger zones such as the subgluteal venous plexus. We believe that using the evidence to guide surgical decision-making is the key to maximizing fat grafting success. Level of Evidence: 4.

Achieving an Optimal Outcome in Immediate Breast Reconstruction

ABSTRACT

Performing immediate breast reconstruction requires careful consideration of preoperative, intraoperative, and postoperative factors. One of the fundamental necessities is a well-coordinated multidisciplinary team to achieve successful reconstruction. Clear and effective communication between the oncological surgeon and plastic surgeon is imperative. The treatment plan must take into account any potential neoadjuvant and adjuvant therapies. Surgical planning and incisional approach must be carefully considered to optimize a safe oncologic surgery and ensure a viable reconstructive outcome. Furthermore, there are fundamentals to immediate breast reconstruction that must be met to obtain an aesthetically pleasing and structurally durable breast reconstruction. The goal of this article was to highlight important considerations in surgical planning and execution of immediate breast reconstruction so that an optimal outcome can be accomplished after either autologous or implant-based breast reconstruction.

Fat Grafting in Breast Reconstruction

The past two decades have witnessed a growing application of autologous fat grafting in the setting of breast reconstruction after surgical treatment of breast cancer. While traditionally used to correct contour deformities during secondary revisions, fat grafting has since evolved to achieve desired breast shape and size both as a complementary adjunct to established reconstructive techniques as well as a standalone technique for whole breast reconstruction. In this article, we will review fat grafting as an adjunct to autologous and implant-breast based reconstruction, an option for primary breast reconstruction, and a treatment of postmastectomy pain.