Rationale for the design of 3D-printable bioresorbable tissue-engineering chambers to promote the growth of adipose tissue

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.

Tissue engineering strategies for breast reconstruction: a literature review of current advances and future directions

Background and Objective

Mastectomy is a primary treatment for breast cancer patients, and both autologous and implant-based reconstructive techniques have shown excellent results. In recent years, advancements in bioengineering have led to a proliferation of innovative approaches to breast reconstruction. This article comprehensively explores the promising perspectives offered by bioengineering and tissue engineering in the field of breast reconstruction.

Methods

A literature review was conducted between April and June 2023 on PubMed and Google Scholar Databases. All English and French articles related to bioengineering applied to the field of breast reconstruction were included. We used the Evidence-Based Veterinary Medicine Association (EBVM) Toolkit 14 checklist for narrative reviews as a quality assurance measure and the Scale for the Assessment of Narrative Review Articles (SANRA) tool to self-assess our methodology.

Key Content and Findings

Over 130 references related to breast bioengineering were included. The analysis revealed four key applications: enhancing the quality of the skin envelope, improving the viability of fat grafting, creating breast shape and volume via bio-printing, and optimizing nipple reconstruction through engineering techniques. The primary identified approaches revolved around establishing structural support and enhancing cellular viability. Structural techniques predominantly involved the implementation of 3D printed, decellularized, or biocompatible material scaffolds. Meanwhile, promoting cellular content trophicity primarily focused on harnessing the regenerative potential of adipose-derived stem cells (ADSCs) and increasing the tissue's survivability and cell trophicity.

Conclusions

Tissue and bioengineering hold immense promise in the field of breast reconstruction, offering a diverse array of approaches. By combining existing techniques with novel advancements, they have the potential to significantly enhance the therapeutic options available to plastic and reconstructive surgeons.

Engineering 3D-Printed Bioresorbable Scaffold to Improve Non-Vascularized Fat Grafting: A Proof-of-Concept Study

Autologous fat grafting is the gold standard for treatment in patients with soft-tissue defects. However, the technique has a major limitation of unpredictable fat resorption due to insufficient blood supply in the initial phase after transplantation. To overcome this problem, we investigated the capability of a medical-grade poly L-lactide-co-poly ε-caprolactone (PLCL) scaffold to support adipose tissue and vascular regeneration. Deploying FDM 3D-printing, we produced a bioresorbable porous scaffold with interconnected pore networks to facilitate nutrient and oxygen diffusion. The compressive modulus of printed scaffold mimicked the mechanical properties of native adipose tissue. In vitro assays demonstrated that PLCL scaffolds or their degradation products supported differentiation of preadipocytes into viable mature adipocytes under appropriate induction. Interestingly, the chorioallantoic membrane assay revealed vascular invasion inside the porous scaffold, which represented a guiding structure for ingrowing blood vessels. Then, lipoaspirate-seeded scaffolds were transplanted subcutaneously into the dorsal region of immunocompetent rats (n = 16) for 1 or 2 months. The volume of adipose tissue was maintained inside the scaffold over time. Histomorphometric evaluation discovered small- and normal-sized perilipin+ adipocytes (no hypertrophy) classically organized into lobular structures inside the scaffold. Adipose tissue was surrounded by discrete layers of fibrous connective tissue associated with CD68+ macrophage patches around the scaffold filaments. Adipocyte viability, assessed via TUNEL staining, was sustained by the presence of a high number of CD31-positive vessels inside the scaffold, confirming the CAM results. Overall, our study provides proof that 3D-printed PLCL scaffolds can be used to improve fat graft volume preservation and vascularization, paving the way for new therapeutic options for soft-tissue defects.

Breast Tissue Reconstruction Using Polycaprolactone Ball Scaffolds in a Partial Mastectomy Pig Model

BACKGROUND

Breast cancer patients suffer from lowered quality of life (QoL) after surgery. Breast conservancy surgery (BCS) such as partial mastectomy is being practiced and studied as an alternative to solve this problem. This study confirmed breast tissue reconstruction in a pig model by fabricating a 3-dimensional (3D) printed Polycaprolactone spherical scaffold (PCL ball) to fit the tissue resected after partial mastectomy.

METHODS

A 3D printed Polycaprolactone spherical scaffold with a structure that can help adipose tissue regeneration was produced using computer-aided design (CAD). A physical property test was conducted for optimization. In order to enhance biocompatibility, collagen coating was applied and a comparative study was conducted for 3 months in a partial mastectomy pig model.

RESULTS

In order to identify adipose tissue and fibroglandular tissue, which mainly constitute breast tissue, the degree of adipose tissue and collagen regeneration was confirmed in a pig model after 3 months. As a result, it was confirmed that a lot of adipose tissue was regenerated in the PCL ball, whereas more collagen was regenerated in the collagen-coated Polycaprolactone spherical scaffold (PCL-COL ball). In addition, as a result of confirming the expression levels of TNF-a and IL-6, it was confirmed that PCL ball showed higher levels than PCL-COL ball.

CONCLUSION

Through this study, we were able to confirm the regeneration of adipose tissue through a 3-dimensional structure in a pig model. Studies were conducted on medium and large-sized animal models for the final purpose of clinical use and reconstruction of human breast tissue, and the possibility was confirmed.

Gluteal Propeller Perforator Flaps: A Paradigm Shift in Abdominoperineal Amputation Reconstruction

Abdominoperineal amputation (AAP) is a gold standard procedure treating advanced abdominal and pelvic cancers. The defect resulting from this extensive surgery must be reconstructed to avoid complications, such as infection, dehiscence, delayed healing, or even death. Several approaches can be chosen depending on the patient. Muscle-based reconstructions are a reliable solution but are responsible for additional morbidity for these fragile patients. We present and discuss our experience in AAP reconstruction using gluteal-artery-based propeller perforator flaps (G-PPF) in a case series. Between January 2017 and March 2021, 20 patients received G-PPF reconstruction in two centers. Either superior gluteal artery (SGAP)- or inferior artery (IGAP)-based perforator flaps were performed depending on the best configuration. Preoperative, intraoperative, and postoperative data were collected. A total of 23 G-PPF were performed-12 SGAP and 11 IGAP flaps. Final defect coverage was achieved in 100% of cases. Eleven patients experienced at least one complication (55%), amongst whom six patients (30%) had delayed healing, and three patients (15%) had at least one flap complication. One patient underwent a new surgery at 4 months for a perineal abscess under the flap, and three patients died from disease recurrence. Gluteal-artery-based propeller perforator flaps are an effective and modern surgical procedure for AAP reconstruction. Their mechanic properties, in addition to their low morbidity, make them an optimal technique for this purpose; however, technical skills are needed, and closer surveillance with patient compliance is critical to ensure success. G-PPF should be widely used in specialized centers and considered a modern alternative to muscle-based reconstructions.

3D bioprinting and the revolution in experimental cancer model systems-A review of developing new models and experiences with in vitro 3D bioprinted breast cancer tissue-mimetic structures

Growing evidence propagates those alternative technologies (relevant human cell-based-e.g., organ-on-chips or biofabricated models-or artificial intelligence-combined technologies) that could help in vitro test and predict human response and toxicity in medical research more accurately. In vitro disease model developments have great efforts to create and serve the need of reducing and replacing animal experiments and establishing human cell-based in vitro test systems for research use, innovations, and drug tests. We need human cell-based test systems for disease models and experimental cancer research; therefore, in vitro three-dimensional (3D) models have a renaissance, and the rediscovery and development of these technologies are growing ever faster. This recent paper summarises the early history of cell biology/cellular pathology, cell-, tissue culturing, and cancer research models. In addition, we highlight the results of the increasing use of 3D model systems and the 3D bioprinted/biofabricated model developments. Moreover, we present our newly established 3D bioprinted luminal B type breast cancer model system, and the advantages of in vitro 3D models, especially the bioprinted ones. Based on our results and the reviewed developments of in vitro breast cancer models, the heterogeneity and the real in vivo situation of cancer tissues can be represented better by using 3D bioprinted, biofabricated models. However, standardising the 3D bioprinting methods is necessary for future applications in different high-throughput drug tests and patient-derived tumour models. Applying these standardised new models can lead to the point that cancer drug developments will be more successful, efficient, and consequently cost-effective in the near future.

Evaluation of satisfaction and the quality of life after bilateral breast reconstruction using the BREAST-Q questionnaire

BACKGROUND

The demand of breast reconstruction is growing, the purpose of this study is to evaluate the satisfaction and quality of life of patients who underwent bilateral breast reconstruction.

METHODS

In this cohort retrospective study, patients who underwent bilateral breast reconstruction in our department between September 2009 and December 2019 were asked to complete BREAST-Q questionnaire based on the timing of the reconstruction received following mastectomy, thus dividing them into three groups: (1) bilateral immediate breast reconstruction(BIBR), (2) immediate breast reconstruction in one side and delayed reconstruction on the other side (mixed group), (3) bilateral delayed breast reconstruction(BDBR). Surgical techniques were divided into prosthesthetic (permanent implant and expander), flaps (pedicle or free), mixed technique (associating flap and prosthesis).

RESULTS

Seventy-one out of 94 patients responded to our BREAST-Q questionnaire, with a response rate of 84.5%. A high score is associated with a better result, except in physical well-being where a lower score indicates better outcome. The average score for psychosocial well-being is 63.0 (±17.2) achieving the lowest among the BDBR group. Physical well-being score is 26.0 (±18.6) scoring the highest in BIBR group. Sexual well-being score is 52.2 (±17.4) and seen highest among BDBR group. Satisfaction with breast score is 54.1 (±10.0) and was highest among mixed group.

CONCLUSION

The therapeutic proposal was personalized based on patient profile and choice. The best reconstruction treatment enhancing the quality of life and patient satisfaction remains the option chosen by the patient and whose advantages and disadvantages are accepted by them.

Techniques and Innovations in Flap Engineering: A Review

Currently, the gold standard for complex defect reconstruction is autologous tissue flaps, with vascularized composite allografts as its highest level. Good clinical results are obtained despite considerable obstacles, such as limited donor sites, donor site morbidity, and complex operations. Researchers in the field of tissue engineering are trying to generate novel tissue flaps requiring small or no donor site sacrifice. At the base of existing technologies is the tissue’s potential for regeneration and neovascularization.

Design of an elastic porous injectable biomaterial for tissue regeneration and volume retention

Soft tissue reconstruction currently relies on two main approaches, one involving the implantation of external biomaterials and the second one exploiting surgical autologous tissue displacement. While both methods have different advantages and disadvantages, successful long-term solutions for soft tissue repair are still limited. Specifically, volume retention over time and local tissue regeneration are the main challenges in the field. In this study the performance of a recently developed elastic porous injectable (EPI) biomaterial based on crosslinked carboxymethylcellulose is analyzed. Nearly quantitative volumetric stability, with over 90% volume retention at 6 months, is observed, and the pore space of the material is effectively colonized with autologous fibrovascular tissue. A comparative analysis with hyaluronic acid and collagen-based clinical reference materials is also performed. Mechanical stability, evidenced by a low-strain elastic storage modulus (G') approaching 1kPa and a yield strain of several tens of percent, is required for volume retention in-vivo. Macroporosity, along with in-vivo persistence of at least several months, is instead needed for successful host tissue colonization. This study demonstrates the importance of understanding material design criteria and defines the biomaterial requirements for volume retention and tissue colonization in soft tissue regeneration. STATEMENT OF SIGNIFICANCE: We present the design of an elastic, porous, injectable (EPI) scaffold suspension capable of inducing a precisely defined, stable volume of autologous connective tissue in situ. It combines volume stability and vascularized tissue induction capacity known from bulk scaffolds with the ease of injection in shear yielding materials. By comparative study with a series of clinically established biomaterials including a wound healing matrix and dermal fillers, we establish design rules regarding rheological and compressive mechanical properties as well as degradation characteristics that rationally underpin the volume stability and tissue induction in a high-performance biomaterial. These design rules should allow to streamline the development of new colonizable injectables.

Current Advances in 3D Bioprinting for Cancer Modeling and Personalized Medicine

Tumor cells evolve in a complex and heterogeneous environment composed of different cell types and an extracellular matrix. Current 2D culture methods are very limited in their ability to mimic the cancer cell environment. In recent years, various 3D models of cancer cells have been developed, notably in the form of spheroids/organoids, using scaffold or cancer-on-chip devices. However, these models have the disadvantage of not being able to precisely control the organization of multiple cell types in complex architecture and are sometimes not very reproducible in their production, and this is especially true for spheroids. Three-dimensional bioprinting can produce complex, multi-cellular, and reproducible constructs in which the matrix composition and rigidity can be adapted locally or globally to the tumor model studied. For these reasons, 3D bioprinting seems to be the technique of choice to mimic the tumor microenvironment in vivo as closely as possible. In this review, we discuss different 3D-bioprinting technologies, including bioinks and crosslinkers that can be used for in vitro cancer models and the techniques used to study cells grown in hydrogels; finally, we provide some applications of bioprinted cancer models.

Overcoming functional challenges in autologous and engineered fat grafting trends

Autologous fat grafting offers significant promise for the repair of soft tissue deformities; however, high resorption rates indicate that engineered solutions are required to improve adipose tissue (AT) survival. Advances in material development and biofabrication have laid the foundation for the generation of functional AT constructs; however, a balance needs to be struck between clinically feasible delivery and improved structural integrity of the grafts. A new approach combining the objectives from both the clinical and research communities will assist in developing morphologically and genetically mature AT constructs, with controlled spatial arrangement and increased potential for neovascularization. In a rapidly progressing field, this review addresses research in both the preclinical and bioengineering domains and assesses their ability to resolve functional challenges.