Angiogenesis Is Differentially Modulated by Platelet-Derived Products

It is not waste if it is therapy: cellular, secretory and functional properties of reamer-irrigator-aspirator (RIA)-derived autologous bone grafts

BACKGROUND

Large bone defects resulting from trauma, disease, or resection often exceed the intrinsic capacity of bones to heal. The current gold standard addressing these defects is autologous bone grafting (ABG). Procedures such as reamer-irrigator-aspirator (RIA) and conventional bone grafting from the iliac crest are widely recognized as highly effective interventions for critical-size bone defects. The early phase of fracture healing is particularly crucial, as it can determine whether a complete bony union occurs, or if delayed healing or non-unions develop. The initial composition of the bone marrow (BM)-rich ABG transplant, with its unique cellular (e.g., leukocytes, monocytes, and granulocytes) and acellular (e.g., growth factors and extracellular proteins) components, plays a key role in this process. However, despite many successful case reports, the role of ABG cells, growth factors, and their precise contributions to bone healing remain largely elusive.

MATERIALS AND METHODS

We characterized the native cellularity of both solid and liquid RIA-derived ABG by analyzing primary, minimally manipulated populations of monocytes, macrophages, and T cells, as well as hematopoietic, endothelial, and mesenchymal progenitor cells by flow cytometry. Growth factor and cytokine contents were assessed through antibody arrays. Possible functional and immunomodulatory properties of RIA liquid were evaluated in functional in vitro assays.

RESULTS

Growth factor and protein arrays revealed a plethora of soluble factors that can be linked to specific immunomodulatory and angiogenic properties, which were evaluated for their potency using functional in vitro assays. We could demonstrate a strong M2-macrophage phenotype inducing the effect of RIA liquid on macrophages. Additionally, we observed an increase in anti-inflammatory T cell subsets generated from peripheral blood mononuclear cells and BM mononuclear cells upon stimulation with RIA liquid . Finally, in vitro endothelial tube formation assays revealed highly significant angiogenic properties of RIA liquid, even at further dilutions.

CONCLUSION

The cytokine and protein content of RIA liquid exhibits potent immunomodulatory and angiogenic properties. These findings suggest significant therapeutic potential for RIA liquid in modulating immune responses and promoting angiogenesis. Anti-inflammatory and angiogenic properties demonstrated in this study might also help to further define and understand its particular mode of action while also providing explanations to the excellent bone-healing properties of ABG in general.

LEVEL OF EVIDENCE

Case-series (Level 4).

Bioactivity of dressings based on platelet-rich plasma and Platelet-rich fibrin for tissue regeneration in animal model

BACKGROUND

Skin wounds are common injuries that affect quality of life and incur high costs. A considerable portion of healthcare resources in Western countries is allocated to wound treatment, mainly using mechanical, biological, or artificial dressings. Biological and artificial dressings, such as hydrogels, are preferred for their biocompatibility. Platelet concentrates, such as platelet-rich plasma (PRP) and platelet-rich fibrin (PRF), stand out for accelerating tissue repair and minimizing risks of allergies and rejection. This study developed PRF and PRP-based dressings to treat skin wounds in an animal model, evaluating their functionality and efficiency in accelerating the tissue repair process.

AIM

To develop wound dressings based on platelet concentrates and evaluating their efficiency in treating skin wounds in Wistar rats.

METHODS

Wistar rats, both male and female, were subjected to the creation of a skin wound, distributed into groups (n = 64/group), and treated with Carbopol (negative control); PRP + Carbopol; PRF + Carbopol; or PRF + CaCl2 + Carbopol, on days zero (D0), D3, D7, D14, and D21. PRP and PRF were obtained only from male rats. On D3, D7, D14, and D21, the wounds were analyzed for area, contraction rate, and histopathology of the tissue repair process.

RESULTS

The PRF-based dressing was more effective in accelerating wound closure early in the tissue repair process (up to D7), while PRF + CaCl2 seemed to delay the process, as wound closure was not complete by D21. Regarding macroscopic parameters, animals treated with PRF + CaCl2 showed significantly more crusting (necrosis) early in the repair process (D3). In terms of histopathological parameters, the PRF group exhibited significant collagenization at the later stages of the repair process (D14 and D21). By D21, fibroblast proliferation and inflammatory infiltration were higher in the PRP group. Animals treated with PRF + CaCl2 experienced a more pronounced inflammatory response up to D7, which diminished from D14 onwards.

CONCLUSION

The PRF-based dressing was effective in accelerating the closure of cutaneous wounds in Wistar rats early in the process and in aiding tissue repair at the later stages.

Optimizing the regenerative potential of vaginal fibroblasts: The role of autologous platelet-rich plasma and hyaluronic acid in vitro

OBJECTIVE

Many postmenopausal women suffering from vulvovaginal atrophy are looking for non-hormonal treatments. Platelet-rich plasma (PRP) therapy has emerged as a novel and promising approach for gynecological applications. PRP is an autologous blood product rich in growth factors used to stimulate tissue regeneration. On the other hand, hyaluronic acid (HA) is used as a treatment for vaginal dryness as it improves tissue hydration thanks to its strong capacity to retain water. This study examines the in vitro effects of PRP alone or combined with HA on vaginal fibroblasts (VFs) isolated from mucosal samples of postmenopausal women undergoing surgery for vaginal prolapse.

METHODOLOGY

Vaginal and blood samples were collected from postmenopausal women undergoing pelvic organ prolapse surgery. PRP was prepared alone or combined with HA (PRP-HA) from peripheral blood. Vaginal fibroblasts were isolated via enzymatic dissociation and cultured in 2D and 3D (spheroids) systems. Biological activities were assessed by measuring cell growth, proliferation, senescence, metabolic activity, and collagen accumulation, along with immunocytochemistry for (myo-)fibroblast markers.

RESULTS

VFs cultured with PRP or PRP-HA showed dose-dependent higher proliferation compared with the control condition, with increased S and G2M cell cycle phases correlating with enhanced proliferation. Expression of vimentin, a protein that plays a key role in maintaining cellular structure and function, was stable, while alpha-SMA decreased, indicating a shift from myofibroblasts to fibroblasts. Collagen production, crucial for wound healing and tissue regeneration, increased under PRP or PRP-HA treatment. PRP and PRP-HA also prevented cell senescence in long-term low-density cultures. These findings were consistent across 2D and 3D culture systems.

CONCLUSIONS

This study provides in vitro evidence supporting the potential of PRP and PRP-HA as autologous treatments for vaginal rejuvenation.

Comprehensive analysis of secretome and transcriptome stability of Wharton jelly mesenchymal stromal cells during good manufacturing practice-compliant production

BACKGROUND

Mesenchymal stromal cells (MSCs) hold promise for cell-based therapies due to their ability to stimulate tissue repair and modulate immune responses. Umbilical cord-derived MSCs from Wharton jelly (WJ) offer advantages such as low immunogenicity and potent immune modulatory effects. However, ensuring consistent quality and safety throughout their manufacturing process remains critical. RNA sequencing (RNA-seq) emerges as a crucial tool for assessing genetic stability and expression dynamics in cell-based therapeutic products.

METHODS

We examined the secretome and transcriptome of WJ-MSC signatures throughout Good Manufacturing Practice (GMP) production, focusing on the performance of total RNA or Massive Analysis of cDNA Ends (MACE) sequencing.

RESULTS

Through extensive transcriptomic analysis, we demonstrated consistent stability of WJ-MSC expression signatures across different manufacturing stages. Notably, MACE-seq showed improved identification of key expression patterns related to senescence and immunomodulation.

CONCLUSIONS

These findings highlight the potential of MACE-seq as a quality assessment tool for WJ-MSC-based therapies, ensuring their efficacy and safety in clinical applications. Importantly, MACE-seq demonstrated its value in characterizing WJ-MSC-derived products, offering insights that traditional assays cannot provide.

Advanced repair of recurrent and low-large hysterotomy defects using a myometrial glide flap

BACKGROUND

The resolution of factors linked to the recurrence of cesarean section defects can be accomplished through a comprehensive technique that effectively addresses the dehiscent area, eliminates associated intraluminal fibrosis, and establishes a vascularized anterior wall by creating a sliding myometrial flap.

OBJECTIVE

Propose a comprehensive surgical repair for recurrent and large low hysterotomy defects in women seeking pregnancy or recurrent spotting.

STUDY DESIGN

A retrospective cohort analysis included 54 patients aged 25-41 with recurrent large cesarean scar defects treated at Otamendi, CEMIC, and Valle de Lili hospitals. Comprehensive surgical repair was performed by suprapubic laparotomy, involving a wide opening of the vesicouterine space, removal of the dehiscent cesarean scar and all intrauterine abnormal fibrous tissues, using a glide myometrial flap, and intramyometrial injection of autologous platelet-rich plasma. Qualitative variables were determined, and descriptive statistics were employed to analyze the data in absolute frequencies or percentages. The data obtained were processed using the InfostatTM statistic program.

RESULTS

Following the repair, all women experienced normal menstrual cycles and demonstrated an adequate lower uterine segment thickness, with no evidence of healing defects. All patients experienced early ambulation and were discharged within 24 h. Uterine hemostasis was achieved at specific points, minimizing the use of electrocautery. The standard duration of the procedure was 60 min (skin-to-skin), and the average bleeding was 80-100 ml. No perioperative complications were recorded. A control T2-weighted MRI was performed six months after surgery. All patients displayed a clean, unobstructed endometrial cavity with a thick anterior wall (Median: 14.98 mm, IQR 13-17). Twelve patients became pregnant again, all delivered by cesarean between 36.1 and 38.0 weeks, with a mean of 37.17 weeks. The thickness of the uterine segment before cesarean ranged between 3 and 7 mm, with a mean of 3.91 mm. No cases of placenta previa, dehiscence, placenta accreta spectrum (PAS), or postpartum hemorrhage were reported.

CONCLUSIONS

The comprehensive repair of recurrent low-large defects offers a holistic solution for addressing recurrent hysterotomy defects. Innovative repair concepts effectively address the wound defect and associated fibrosis, ensuring an appropriate myometrial thickness through a gliding myometrial flap.

Application of Platelet-Rich Plasma as a Stem Cell Treatment - an Attempt to Clarify a Common Public Misconception

In recent years, there has been a significant increase in the practice of regenerative medicine by health practitioners and direct-to-consumer businesses globally. Among different tools of regenerative medicine, platelet-rich plasma (PRP) and stem cell-based therapies have received considerable attention. The use of PRP, in particular, has gained popularity due to its easy access, simple processing techniques, and regenerative potential. However, it is important to address a common misconception amongst the general public equating to PRP and stem cells due to the demonstrated efficacy of PRP in treating musculoskeletal and dermatological disorders. Notably, PRP promotes regeneration by providing growth factors or other paracrine factors only. Therefore, it cannot replenish or replace the lost cells in conditions where a large number of cells are required to regenerate tissues and/or organs. In such cases, cellbased therapies are the preferred option. Additionally, other tools of regenerative medicine, such as bioprinting, organoids, and mechanobiology also rely on stem cells for their success. Hence, healthcare and commercial entities offering direct-to-customer regenerative therapies should not mislead the public by claiming that the application of PRP is a stem cell-based therapy. Furthermore, it is important for regulatory bodies to strictly monitor these profit-driven entities to prevent them from providing unregulated regenerative treatments and services that claim a broad variety of benefits with little proof of efficacy, safety concerns, and obscure scientific justification.

A Comprehensive Look at In Vitro Angiogenesis Image Analysis Software

One of the complex challenges faced presently by tissue engineering (TE) is the development of vascularized constructs that accurately mimic the extracellular matrix (ECM) of native tissue in which they are inserted to promote vessel growth and, consequently, wound healing and tissue regeneration. TE technique is characterized by several stages, starting from the choice of cell culture and the more appropriate scaffold material that can adequately support and supply them with the necessary biological cues for microvessel development. The next step is to analyze the attained microvasculature, which is reliant on the available labeling and microscopy techniques to visualize the network, as well as metrics employed to characterize it. These are usually attained with the use of software, which has been cited in several works, although no clear standard procedure has been observed to promote the reproduction of the cell response analysis. The present review analyzes not only the various steps previously described in terms of the current standards for evaluation, but also surveys some of the available metrics and software used to quantify networks, along with the detection of analysis limitations and future improvements that could lead to considerable progress for angiogenesis evaluation and application in TE research.

Angiogenesis and Tissue Repair Depend on Platelet Dosing and Bioformulation Strategies Following Orthobiological Platelet-Rich Plasma Procedures: A Narrative Review

Angiogenesis is the formation of new blood vessel from existing vessels and is a critical first step in tissue repair following chronic disturbances in healing and degenerative tissues. Chronic pathoanatomic tissues are characterized by a high number of inflammatory cells; an overexpression of inflammatory mediators; such as tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1); the presence of mast cells, T cells, reactive oxygen species, and matrix metalloproteinases; and a decreased angiogenic capacity. Multiple studies have demonstrated that autologous orthobiological cellular preparations (e.g., platelet-rich plasma (PRP)) improve tissue repair and regenerate tissues. There are many PRP devices on the market. Unfortunately, they differ greatly in platelet numbers, cellular composition, and bioformulation. PRP is a platelet concentrate consisting of a high concentration of platelets, with or without certain leukocytes, platelet-derived growth factors (PGFs), cytokines, molecules, and signaling cells. Several PRP products have immunomodulatory capacities that can influence resident cells in a diseased microenvironment, inducing tissue repair or regeneration. Generally, PRP is a blood-derived product, regardless of its platelet number and bioformulation, and the literature indicates both positive and negative patient treatment outcomes. Strangely, the literature does not designate specific PRP preparation qualifications that can potentially contribute to tissue repair. Moreover, the literature scarcely addresses the impact of platelets and leukocytes in PRP on (neo)angiogenesis, other than a general one-size-fits-all statement that "PRP has angiogenic capabilities". Here, we review the cellular composition of all PRP constituents, including leukocytes, and describe the importance of platelet dosing and bioformulation strategies in orthobiological applications to initiate angiogenic pathways that re-establish microvasculature networks, facilitating the supply of oxygen and nutrients to impaired tissues.

Ultrasound-guided platelet-rich-plasma injections for reducing sacroiliac joint pain: A paradigmatic case report and literature review

BACKGROUND

Sacro-iliac joint (SIJ) pain is an often-misdiagnosed cause (up to 30% cases) of atypical low back pain (LBP) that might be treated with a wide range of conservative interventions. However, Platelet-Rich-Plasma (PRP) ultrasound-guided injections at SIJ level in subjects with mitochondrial disorders have not yet been investigated.

CASE PRESENTATION

A 52-year-old Caucasian male with fluoroquinolone-related mitochondrial dysfunction referred to a Physical Medicine and Rehabilitation Outpatient, complaining of severe SIJ pain (Numeric Pain Related Scale, NPRS=8). We performed two bilateral PRP ultrasound-guided injections at the sacro-iliac level. PRP is a simple, efficient, and minimally invasive approach. After the first PRP injection, there was a considerable reduction of pain (NPRS=8 vs 5). The second PRP infiltration was performed after 2 weeks and in both cases no adverse events. At the 6-month follow-up evaluation, the patient showed good physical recovery, with the absence of pain (NPRS=0).

CONCLUSION

To the best of our knowledge, this is the first report in the literature assessing the safety and effectiveness of PRP ultrasound-guided injections for SIJ pain in a patient affected by mitochondrial disorders. Thus, this case report might have relevant clinical implications in the treatment of SIJ pain in patients affected by this rare pathological condition, albeit further observational studies are warranted to confirm these findings.

Swiss Medical Devices for Autologous Regenerative Medicine: From Innovation to Clinical Validation

Regenerative medicine, based on the use of autologous tissues and embryonic, stem or differentiated cells, is gaining growing interest. However, their preparation, in a manner compliant with good practices and health regulations, is a technical challenge. The aim of this manuscript is to present the design of reliable CE marked medical devices for the preparation of standardized platelet-rich plasma (PRP) and other autologous biologics intended for therapeutic uses. There are numerous PRP isolation processes. Depending on the methodology used, PRP composition varies greatly in terms of platelet concentration, platelet quality, and level of contamination with red and white blood cells. This variability in PRP composition might affect the clinical outcomes. The devices presented here are based on a specific technology, patented all over the world, that allows the precise separation of blood components as a function of their density using thixotropic separator gels in closed systems. This allows the preparation, in an automated manner, of leukocyte poor PRP with a standardized composition. Production of different forms of PRP is a clinical asset to suit various therapeutic needs. Therefore, we are offering solutions to prepare PRP either in liquid or gel form, and PRP combined with hyaluronic acid. These biologics have been successfully used in many different therapeutic domains, resulting in more than 150 published clinical studies. We also developed the CuteCell technology platform for cell culture expansion for further autologous cell therapies. This technology enables the safe and rapid in vitro expansion of cells intended for therapeutic use in good manufacturing practices (GMP) and autologous conditions, using blood-derived products as culture media supplementation. We summarize in this article our 20 years’ experience of research and development for the design of PRP devices and, more recently, for PRP combined with hyaluronic acid.

Proteomics reveals differential adsorption of angiogenic platelet lysate proteins on calcium phosphate bone substitute materials

Protein adsorption on biomaterials for bone substitution, such as calcium phosphates (CaP), evokes biological responses and shapes the interactions of biomaterials with the surrounding biological environment. Proteins adsorb when CaP materials are combined with growth factor-rich hemoderivatives prior to implantation to achieve enhanced angiogenesis and stimulate new bone formation. However, the identification of the adsorbed proteins and their angiogenic effect on bone homeostasis remain incompletely investigated. In this study, we analyzed the adsorbed complex protein composition on CaP surfaces when using the hemoderivatives plasma, platelet lysate in plasma (PL), and washed platelet lysate proteins (wPL). We detected highly abundant, non-regenerative proteins and anti-angiogenic proteins adsorbed on CaP surfaces after incubation with PL and wPL by liquid chromatography and mass spectrometry (LC–MS) proteomics. Additionally, we measured a decreased amount of adsorbed pro-angiogenic growth factors. Tube formation assays with human umbilical endothelial cells demonstrated that the CaP surfaces only stimulate an angiogenic response when kept in the hemoderivative medium but not after washing with PBS. Our results highlight the necessity to correlate biomaterial surfaces with complex adsorbed protein compositions to tailor the biomaterial surface toward an enrichment of pro-angiogenic factors.