Pectus excavatum camouflage: a new technique using a tissue engineered scaffold

Conceptualizing Scaffold Guided Breast Tissue Regeneration in a Preclinical Large Animal Model

Scaffold-guided breast tissue regeneration (SGBTR) can transform both reconstructive and cosmetic breast surgery. Implant-based surgery is the most common method. However, there are inherent limitations, as it involves replacement of tissue rather than regeneration. Regenerating autologous soft tissue has the potential to provide a more like-for-like reconstruction with minimal morbidity. Our SGBTR approach regenerates soft tissue by implanting additively manufactured bioresorbable scaffolds filled with autologous fat graft. A pre-clinical large animal study was conducted by implanting 100 mL breast scaffolds (n = 55) made from medical-grade polycaprolactone into 11 minipigs for 12 months. Various treatment groups were investigated where immediate or delayed autologous fat graft, as well as platelet rich plasma, were added to the scaffolds. Computed tomography and magnetic resonance imaging were performed on explanted scaffolds to determine the volume and distribution of the regenerated tissue. Histological analysis was performed to confirm the tissue type. At 12 months, we were able to regenerate and sustain a mean soft tissue volume of 60.9 ± 4.5 mL (95% CI) across all treatment groups. There was no evidence of capsule formation. There were no immediate or long-term post-operative complications. In conclusion, we were able to regenerate clinically relevant soft tissue volumes utilizing SGBTR in a pre-clinical large animal model.

Silicone Pectoral Implant to Solve Aesthetic Chest Deformity After Pectoralis Flap Harvesting for Laryngotracheal Reconstruction

BACKGROUND

 The pectoralis major musculocutaneous flap has been considered for decades the workhorse in head and neck reconstruction. However, the disadvantages of the pectoralis flap include the morbidity of the donor site in terms of cosmetic and functional results. A silicone pectoral implant  can be used to solve such aesthetic chest deformity in male patients.

METHODS

A 33-years-old man with a history of cervical tracheoesophageal fistula after a blunt trauma due to a motorcycle accident, previously reconstructed with a pectoralis major flap, consulted our Plastic Surgery Department for an aesthetic defect of the donor site . The use of an anatomical pectoral implant was planned with the aim of aesthetic reshaping of the male chest. A pocket was created following the preoperative design to position a 190 cc pectoral implant. Dissection was performed in a subcutaneous plane that included the underneath adipose tissue layer and then over the pectoralis minor and the serratus muscle. Three months later, in a second stage, lipofilling of the depressed areas was performed with 100 ml of adipose tissue obtained from the abdomen.

RESULTS

After two years of follow-up, the patient obtained a satisfactory aesthetic result, with an improvement in the projection of the thorax and the symmetry of the body contour. As the implant was placed into the subcutaneous pocket, no functional compromise in shoulder flexion or adduction was detected during follow-up.

CONCLUSIONS

 The pectoral implant technique seems safe and provides reshaping of the male chest wall, significantly improving the cosmetic appearance of the patient. In addition, its use with associated procedures such as lipofilling allows optimal results to be obtained. To the best of our knowledge, this is the first case to describe the use of a pectoral implant to solve donor site morbidity after pectoralis flap harvesting for any reconstructive purpose. Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Convergence of scaffold-guided bone regeneration principles and microvascular tissue transfer surgery

A preclinical evaluation using a regenerative medicine methodology comprising an additively manufactured medical-grade ε-polycaprolactone β-tricalcium phosphate (mPCL-TCP) scaffold with a corticoperiosteal flap was undertaken in eight sheep with a tibial critical-size segmental bone defect (9.5 cm³, M size) using the regenerative matching axial vascularization (RMAV) approach. Biomechanical, radiological, histological, and immunohistochemical analysis confirmed functional bone regeneration comparable to a clinical gold standard control (autologous bone graft) and was superior to a scaffold control group (mPCL-TCP only). Affirmative bone regeneration results from a pilot study using an XL size defect volume (19 cm³) subsequently supported clinical translation. A 27-year-old adult male underwent reconstruction of a 36-cm near-total intercalary tibial defect secondary to osteomyelitis using the RMAV approach. Robust bone regeneration led to complete independent weight bearing within 24 months. This article demonstrates the widely advocated and seldomly accomplished concept of "bench-to-bedside" research and has weighty implications for reconstructive surgery and regenerative medicine more generally.

Additive manufactured macroporous chambers facilitate large volume soft tissue regeneration from adipose-derived extracellular matrix

Breast tissue engineering is a promising alternative intervention for breast reconstruction. Due to their low immunogenicity and well-preserved adipogenic microenvironment, decellularized adipose tissue (DAT) can potentially regenerate adipose tissue in vivo. However, the volume of adipose tissue regenerated from DAT can hardly satisfy the demand for breast reconstruction. Tissue engineering chamber (TEC) is an effective technique for generation of large adipose tissue volumes. However, TEC applications necessitate reoperation to remove non-degradable plastic chambers and harvest autologous tissue flaps, which prolongs the operation time and causes potential damage to donor sites. We improved the TEC strategy by combining bioresorbable polycaprolactone (PCL) chambers and decellularized adipose tissues (DAT). A miniaturized porous PCL chamber was fabricated based on scaling differences between human and rabbit chests, and basic fibroblast growth factor (bFGF)-loaded DAT successfully prepared. In rabbit models, a highly vascularized adipose tissue that nearly filled up the PCL chamber (5 mL) was generated de novo from 0.5 mL bFGF-loaded DAT. The newly formed tissue had significantly high expressions of adipogenic genes, compared to the endogenous adipose tissue. The concept described here can be exploited for breast tissue engineering. STATEMENT OF SIGNIFICANCE: Decellularized adipose tissue (DAT), which provides infiltrated cells adipogenic microenvironment, can potentially regenerate adipose tissue in vivo. Nevertheless, the volume of regenerated adipose tissue is insufficient to repair large sized tissue defect. Tissue engineering chamber (TEC) could provide a protective space for in situ regeneration of large volume tissue. Herein, a new strategy by combining biodegradable polycaprolactone chambers and basic fibroblast growth factor-loaded decellularized adipose tissue is proposed. In rabbit model, newly formed adipose tissue regenerated from DAT successfully filled the dome shaped chamber with ten folds higher volume than DAT, which is proportionally similar to women breast. This work highlighted the importance of adipogenic microenvironment and protective space for adipose tissue regeneration.