Breast reconstruction using tissue expander and TRAM flap with vascular enhancement procedures

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.

Breast reconstruction using delayed pedicled transverse rectus abdominis muscle flap with supercharging: reports of three cases

Breast reconstruction using a pedicled transverse rectus abdominis muscle (TRAM) flap is a well-established surgical procedure. Although studies suggest that transplanting this flap using a delayed method reduces the risk of partial flap necrosis, challenges persist. Hence, we present three cases of breast reconstruction using a pedicled TRAM flap with both delaying and supercharging. Patient age, excised tissue volume for mastectomy, and follow-up period were as follows: Case 1, 58 years, 429 cm³, 5 months; Case 2, 35 years, 910 cm³, 6 months; and Case 3, 56 years, 489 cm³, 4 months. One patient (Case 2) required a large flap tissue volume to achieve breast symmetry, whereas the other two (Cases 1 and 3) had long, longitudinal scars from previous cesareans sections. In a delayed surgery, the flap was partially elevated with partial dissection and no ligation of the deep inferior epigastric artery and vein (DIEAV). An artificial dermis with a silicone membrane (Teldermis^®) was used to prevent adhesion of the rectus abdominal muscles and DIEAV to the surrounding tissue. Supercharging was performed by anastomosis between the ipsilateral DIEAV and internal thoracic AV. Flaps in zones I-III and in half of zone IV for Case 2, and zones I-III for Cases 1 and 3, were transferred; all survived without infection. This method allowed the transferring of a larger tissue volume compared with the conventional pedicled TRAM flap-transfer method. Thus, it may be useful for patients who require larger tissue volume or high-risk patients.

Quantitative assessment and risk factors for chest wall deformity resulting from tissue expansion for breast reconstruction

BACKGROUND

Chest wall deformity after tissue expansion for breast reconstruction is less recognized than complications such as infection, hematoma, skin necrosis and capsular contracture. However, the condition should not be discounted because pain, rib fracture and dyspnea may occur in severe cases. The aim of this study is to evaluate the extent of chest wall deformity quantitatively using computed tomography (CT) and to identify risk factors for this condition after tissue expansion.

METHODS

The subjects were 34 patients who underwent unilateral two-stage reconstruction and were examined by multidetector-row CT before expander surgery and during maximal tissue expansion. Chest wall deformity was assessed quantitatively using the Chest Wall Deformity Index (CWDI), which was measured before expander surgery (pre-CWDI) and during maximal tissue expansion (post-CWDI). Post minus pre (post-pre) CWDI was used as the index of chest wall deformity in the assessment of risk factors.

RESULT

Post-CWDI was significantly higher than pre-CWDI (3.66 ± 3.23% vs. 0.03 ± 2.74%, P < 0.001 by paired t test), showing that chest wall deformity occurred after maximum expansion. In a multiple linear regression model, capsular contracture emerged as a significant predictor of increased post-pre CWDI (P = 0.003). BMI was a significant predictor of decreased post-pre CWDI (P = 0.003), but this result may have been due to the measurement method.

CONCLUSIONS

Our findings suggest that chest wall deformity is common after maximum tissue expansion for breast reconstruction. Awareness of the possibility of chest wall deformity during tissue expansion is important, particularly in cases with capsular contracture.