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Functional and biomechanical recovery of skin following suture closure and LASE sealing in Balb/c mice. (a) Photothermal response of LASE‐skin interface during in vivo sealing irradiated using a continuous wave NIR laser tuned to 808 nm at a laser power density of ~5.1 W/cm². The region shaded in light blue color (temperature range from ~50°C to ~60°C) indicates the optimal temperature window for laser tissue sealing. The photothermal response curve shows data that are a mean of n = 3 independent experiments. (b) Representative images of 1‐cm long skin incisions closed with four, simple interrupted 4‐0 nylon sutures or LASE on Days 0 (immediately after closure), 2, 4, and 7 postwounding; control is unwounded skin surgically prepared similarly to incised skin. (c) Representative image showing three approximate locations at which TEWL measurements were carried out (white arrows) for each type of closure method. (d) Transepidermal water loss (TEWL) of healed skin and unwounded control skin on Days 2, 4, and 7 postwounding. TEWL value (in g/m² h) for each incision type is the average TEWL measurement from three nonoverlapping spots over the incision line shown in b. Data shown are mean ± standard error of the mean of n = 6 mice. (e) Ultimate tensile strength (UTS) and recovery, that is, %UTS of intact skin strength (secondary axis shown in red) of healed skin on Days 2 and 7 postwounding for suture‐closed and LASE‐sealed incisions. Data shown are mean ± standard error of the mean of n = 6 mice. Statistical significance was determined using two‐way ANOVA followed by Fisher's LSD test and individual p values are shown; p < 0.05 are considered statistically significant.
Source publication
Injuries caused by surgical incisions or traumatic lacerations compromise the structural and functional integrity of skin. Immediate approximation and robust repair of skin are critical to minimize occurrences of dehiscence and infection that can lead to impaired healing and further complication. Light‐activated skin sealing has emerged as an alter...
Citations
... As described, we removed residual CTAB and thus our preparations are not expected to induce such responses. Importantly, we have observed that photothermally-activated silk fibroin-based wound dressings progressively slough off incisional wounds and leave no residual photothermal agents within the wound space [33,74]. In the present study, no evidence of GNR or toxicity was noted within the wound area. ...
Slow-healing and chronic wounds represent a major global economic and medical burden, and there is significant unmet need for novel therapies which act to both accelerate wound closure and enhance biomechanical recovery of the skin. Here, we report a new approach in which bioactives that augment early stages of wound healing can kickstart and engender effective wound closure in healthy and diabetic, obese animals, and set the stage for subsequent tissue repair processes. We demonstrate that a nanomaterial dressing made of silk fibroin and gold nanorods (GNR) stimulates a pro-neutrophilic, innate immune, and controlled inflammatory wound transcriptomic response. Further, Silk-GNR, lasered into the wound bed, in combination with exogeneous histamine, accelerates early-stage processes in tissue repair leading to effective wound closure. Silk-GNR and histamine enhanced biomechanical recovery of skin, increased transient neoangiogenesis, myofibroblast activation, epithelial-to-mesenchymal transition (EMT) of keratinocytes and a pro-resolving neutrophilic immune response, which are hitherto unknown activities for these bioactives. Predictive and temporally coordinated delivery of growth factor nanoparticles that modulate later stages of tissue repair further accelerated wound closure in healthy and diabetic, obese animals. Our approach on kickstarting the delivering the “right bioactive at the right time” stimulates a multifactorial, pro-reparative response by augmenting endogenous healing and immunoregulatory mechanisms and, highlights new targets to promote tissue repair.
... The repair of skin wounds after skin injury is vital for the structural and functional recovery of the skin. However, adult skin wounds often scar when healing [1]. Studies have shown that wounds in embryonic skin heal without scarring and that the skin structure and regeneration-associated appendages are reconstructed [2][3][4]. ...
We evaluated the expression profiles of differentially expressed miRNAs (DEmiRNAs) involved in human fetal skin development via high-throughput sequencing to explore the expression difference and the regulatory role of miRNA in different stages of fetal skin development. Analysis of expression profiles of miRNAs involved collecting embryo samples via high-throughput sequencing, then bioinformatics analyses were performed to validate DEmiRNAs. A total of 363 miRNAs were differentially expressed during the early and mid-pregnancy of development, and upregulated DEmiRNAs were mainly concentrated in the let-7 family. The transfection of let-7b-5p slowed down HaCaT cell proliferation and promoted apoptosis, as evidenced by the cell counting kit-8 assay, quantitative real-time polymerase chain reaction, and flow cytometry. The double luciferin reporter assay also confirmed let-7b-5p and ΔNp63 downregulation through the combination with the 3ʹ-untranslated region of ΔNp63. Moreover, treatment with a let-7b-5p inhibitor upregulated ΔNp63 and activated the phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway. The let-7b-5p caused a converse effect on HaCaT cells because of Np63 upregulation. Let-7b-5p regulates skin development by targeting ΔNp63 via PI3K-AKT signaling, contributing to future studies on skin development and clinical scar-free healing.
... Laser tissue soldering represents a promising alternative: it is a surgical technique that combines laser light with a solder paste, a temperature-activatable adhesive material, usually protein-based, to create strong watertight bonds. (18)(19)(20) The attractiveness of soldering lies in its ability to rapidly form bonds with good strength, (21)(22)(23) low inflammatory response, (24) reduced scar tissue formation, (25) and reduced access to pathogens thanks to the creation of a waterproof seal. (26) Furthermore, this technique is, in principle, readily adaptable for minimally invasive procedures. ...
Minimally invasive surgical techniques, including endoscopic and robotic procedures, continue to revolutionize patient care, for their ability to minimize surgical trauma, thus promoting faster recovery and reduced hospital stays. Yet, the suturing of soft tissues ensuring damage-free tissue bonding during these procedures remains challenging due to missing haptics and the fulcrum effect. Laser tissue soldering has potential in overcoming these issues, offering damage-free seamless tissue fusion. To ensure the precision and safety of laser tissue soldering, we introduce feedback controlled fluorescent nanothermometry-guided laser tissue soldering using nanoparticle-protein solders within endoscopic and robotic contexts. Temperature-sensitive fluorescent nanoparticles embedded in the solder provide surgeons with immediate feedback on tissue temperatures during laser application, all while within the confines of minimally invasive (robotic) surgical setups. By integrating fluorescent nanothermometry-guided laser tissue surgery into endoscopic and robotic surgery, we pave the way for a new approach for safe and atraumatic soft tissue joining, especially in regions where traditional suturing is unfeasible.
... Silk fibroin protein was extracted and enriched from Bombyx mori silkworm cocoons purchased from Mulberry Farms, CA, USA, using methods previously described by others [41] and us [42]. Each cocoon was cut into four pieces and the dead insect inside it was discarded. ...
... AuNBP-LASE treatment successfully closed full-thickness incisions, and no visible signs of dehiscence, inflammation, edema, or infection were observed in any mouse for the duration of the study (day 2 post-surgery; Figure 3a). We chose to investigate early time points-day 2 post surgerybecause mouse skin heals rapidly by contraction and significant differences between sutures and laser sealing are not seen at later times following closure [42]. In addition, efficient closure and early functional and biomechanical recovery are important for minimizing opportunistic infections and activating subsequent tissue repair processes, including the resolution of inflammation. ...
... Although the epidermal gap was statistically comparable between the groups, local hyperthermia in the LASE group appeared to compromise the epidermis (Figure 4 right). This epidermal gap is expected to significantly decrease by day 7 based on previous observations [42]. Investigation of tissues stained with Masson's trichrome (collagen stain) indicated denser collagen bundles and loss of typical "basket-weave" pattern observed in the skin adjacent to wound sealed with AuNBP-LASE (Figure 4 bottom) compared to those closed with sutures or unwounded skin; additional histology images of other subjects are shown in Supplementary Figure S4. ...
Anisotropic gold nanostructures have gained increased attention for biomedical applications because of their remarkable optical properties. An emerging type of gold nanostructure—gold nanobipyramids (AuNBP)—has been shown to exhibit superior absorption properties compared to conventionally used gold nanoparticles, which makes them attractive for photothermal applications. We generated a high-shape-purity dispersion of AuNBP using a seed-mediated method and embedded them as photothermal conversion agents in a silk fibroin matrix to investigate their efficacy in photothermal sealing of incisional wounds in immunocompetent mice. These AuNBP-doped laser-activated sealants, or AuNBP-LASE were able to absorb near-infrared laser energy and convert it to heat, thereby inducing transient hyperthermia in the wound and the surrounding tissue. This photothermal conversion facilitated rapid sealing of the skin tissue by the AuNBP-LASE, which resulted in faster functional recovery of skin barrier function compared to nylon sutures at the early stages of repair. Further, the biomechanical properties of the healing skin closed with AuNBP-LASE those of intact skin more rapidly compared to incisions approximated with sutures. Histology studies indicated higher penetration of the LASE within the volume of the incision in skin tissue, lower scab formation, and a similar epidermal gap compared to conventional suturing. These results demonstrate that AuNBP-LASEs can be effective as wound approximation devices for photothermal sealing.
... Traditional PAI uses visible and near infrared (VIS/NIR, 400 to 1000 nm) light to detect endogenous chromophores like hemoglobin and absorbing dyes and nanoparticles like indocyanine green and gold nanorods. [6][7][8] Other optical methods have been employed in this waveband to quantify LWC content in tissue, [9][10][11] however, at superficial tissue depths <1 mm. Additionally, these absorbers are notoriously challenging to quantify in the VIS/NIR window due to their relatively weak optical absorption. ...
... Reflection-mode PA systems with increased capabilities also have promise in clinical environments to aid in the diagnosis of superficial skin lesions relating to skin cancer or tracking the progression of wound healing. 7,53,54 Efforts are underway to incorporate HWG into a novel closed-loop reflection-mode PA system tailored for imaging skin lesions and monitoring wound healing. A patent application has been issued for the HWG interface mechanism as described in this article. ...
Significance
Changes in lipid, water, and collagen (LWC) content in tissue are associated with numerous medical abnormalities (cancer, atherosclerosis, and Alzheimer’s disease). Standard imaging modalities are limited in resolution, specificity, and/or penetration for quantifying these changes. Short-wave infrared (SWIR) photoacoustic imaging (PAI) has the potential to overcome these challenges by exploiting the unique optical absorption properties of LWC>1000 nm.
Aim
This study’s aim is to harness SWIR PAI for mapping LWC changes in tissue. The focus lies in devising a reflection-mode PAI technique that surmounts current limitations related to SWIR light delivery.
Approach
To enhance light delivery for reflection-mode SWIR PAI, we designed a deuterium oxide (D2O, “heavy water”) gelatin (HWG) interface for opto-acoustic coupling, intended to significantly improve light transmission above 1200 nm.
Results
HWG permits light delivery >1 mJ up to 1850 nm, which was not possible with water-based coupling (>1 mJ light delivery up to 1350 nm). PAI using the HWG interface and the Visualsonics Vevo LAZR-X reveals a signal increase up to 24 dB at 1720 nm in lipid-rich regions.
Conclusions
By overcoming barriers related to light penetration, the HWG coupling interface enables accurate quantification/monitoring of biomarkers like LWC using reflection-mode PAI. This technological stride offers potential for tracking changes in chronic diseases (in vivo) and evaluating their responses to therapeutic interventions.
... Release of metabolites for 10-days was determined since, several in vitro scratch assay tests and in vivo mice experiments for acute wound healing have a similar time frame. 31,32 Immunosuppression has been shown to accelerate wound healing. 33 All the three paKG MPs showed a similar type of release kinetics ( Figure 2A) but we have previously demonstrated that 1,10 paKG MPs can lead to immunosuppression, 3 and therefore in this study we tested if these can lead to faster wound healing. ...
Metabolites are not only involved in energy pathways but can also act as signaling molecules. Herein, we demonstrate that polyesters of alpha-ketoglutararte (paKG) can be generated by reacting aKG with aliphatic diols of different lengths, which release aKG in a sustained manner. paKG polymer-based microparticles generated via emulsion-evaporation technique lead to faster keratinocyte wound closures in a scratch assay test. Moreover, paKG microparticles also led to faster wound healing responses in an excisional wound model in live mice. Overall, this study shows that paKG MPs that release aKG in a sustained manner can be used to develop regenerative therapeutic responses.
Minimally invasive surgical techniques, including endoscopic and robotic procedures, continue to revolutionize patient care, for their ability to minimize surgical trauma, thus promoting faster recovery and reduced hospital stays. Yet, the suturing of soft tissues ensuring damage‐free tissue bonding during these procedures remains challenging due to missing haptics and the fulcrum effect. Laser tissue soldering has potential in overcoming these issues, offering atraumatic seamless tissue fusion. To ensure the precision and safety of laser tissue soldering, the study introduces feedback‐controlled fluorescent nanothermometry‐guided laser tissue soldering using nanoparticle‐protein solders within endoscopic and robotic contexts. Temperature‐sensitive fluorescent nanoparticles embedded in the solder provide surgeons with immediate feedback on tissue temperatures during laser application, all while within the confines of minimally invasive (robotic) surgical setups. By integrating fluorescent nanothermometry‐guided laser tissue surgery into endoscopic and robotic surgery, the study paves the way for a new approach for safe and atraumatic soft tissue joining, especially in regions where traditional suturing is unfeasible.
Bioinspired synthetic materials can be designed as reliable, cost‐effective, and fully controlled alternatives to natural biomaterials for treating damaged tissues and organs. However, several hurdles need to be overcome for clinical translation, particularly for biomaterials gelled in situ. These include the potential toxicity of chemical crosslinkers used in the materials' assembly or breakdown products they generate and the challenges of fine‐tuning the mechanical properties of the materials. Here, a minimalistic, adhesive soft material is developed by screening hundreds of potential formulations of self‐assembling, custom‐designed collagen‐like peptide sequences for the in situ formation of tissue‐bonding 3D hydrogels. Nine promising formulations for tissue repair are identified using a low‐volume and rapid combinatory screening approach. It is shown that simply varying the ratio of the two key components promotes adhesion and fine‐tunes the material's mechanical properties. The materials' skin and heart repair capabilities are assessed in vitro and clinically relevant animal models. The materials are also tested for corneal applications using ex vivo pig cornea models complemented by in vitro cell compatibility assays.
