Platelet-rich plasma loaded with antibiotics as an affiliated treatment for infected bone defect by combining wound healing property and antibacterial activity

Antibiotic-Loaded Platelet-Rich Fibrin (AL-PRF) as a New Carrier for Antimicrobials: A Systematic Review of In Vitro Studies

Platelet-rich fibrin (PRF) has emerged as a promising scaffold for drug delivery, particularly in the context of antimicrobial therapies. This systematic review evaluates the incorporation of antibiotics into PRF to determine its efficacy as a localized antimicrobial delivery system compared to plain PRF without antibiotics. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, including 13 in vitro studies with a moderate risk of bias. Antibiotics were incorporated into PRF using different methodologies, including systemic administration before blood collection, addition to blood before centrifugation, and injection into formed PRF matrices. Outcomes were analyzed regarding antibacterial efficacy, structural integrity of PRF, and release kinetics. Antibiotic-enhanced PRF demonstrated significant antibacterial activity against various bacterial strains. The efficacy of the enhanced PRF was dependent on the type of antibiotic, its concentration, and incorporation method. Encapsulation approaches facilitated a sustained antibiotic release, while higher antibiotic concentrations occasionally disrupted PRF integrity. Systemic administration of antibiotics before blood collection enriches PRF effectively, producing significant inhibition zones. The antibacterial effects of PRF outperformed alternative carriers, such as collagen sponges. Antibiotic-loaded PRF is a potent tool for localized antimicrobial delivery, with promising applications in clinical settings. Further research is needed to standardize preparation protocols and explore the impact of different antibiotic delivery methods on PRF's regenerative properties.

The Role of Autologous Platelet Concentrates as a Local Antibiotic Delivery System: A Systematic Scoping Review

OBJECTIVES

Ongoing research has begun to develop innovative approaches to deliver local antibiotics while minimizing systemic side effects, antimicrobial resistance, and limited tissue penetration. Autologous platelet concentrates (APCs) offer promise in delivering antibiotics directly to infection sites. Despite the interest, a comprehensive evaluation of their effectiveness is lacking. Therefore, this systematic scoping review aims to collect and appraise studies regarding the efficacy of APCs in delivering antibiotics.

METHODS

A systematic electronic search of PubMed, Scopus, and Web of Science, using a combination of keywords, was conducted up to February 2024. Articles addressing the use of APCs as a local antibiotic delivery system were included.

RESULTS

A total of 13 articles, including 10 in vitro studies, 1 in vitro and clinical study, 1 ex vivo study, and 1 clinical study, were selected. Antibiotic loading capacity and release was confirmed in all studies using doxycycline, gentamicin, linezolid, vancomycin, metronidazole, and penicillin. In addition, the antibacterial effect was obtained mainly against E. coli., P. aeruginosa, S. mitis, H. influenzae, S. pneumoniae, and S. aureus.

CONCLUSIONS

The incorporation of antibiotics into APCs has been proven to facilitate the effective release of antimicrobial agents at optimal concentrations, potentially reducing the incidence of post-operative infections, substituting, or augmenting systemic antibiotic treatment while retaining APCs' inherent healing properties.

Modified minimally invasive surgical technique with clindamycin-augmented or non-augmented platelet-rich fibrin in periodontal regeneration: A randomized clinical trial

AIM

Injectable platelet-rich fibrin (I-PRF), a second-generation platelet concentrate, is widely used to enhance soft and hard tissue healing alone or in combination with biomaterials, relying on its harboring of various pivotal growth/differentiation factors. This randomized trial assessed the effect of clindamycin (CLN) augmented injectable platelet-rich fibrin (I-PRF) with modified minimally invasive surgical technique (M-MIST) versus I-PRF alone with M-MIST on the clinical and radiographic parameters in the management of periodontal intra-bony defects in patients with stage-III grade B periodontitis.

METHODS

This is a 9-month parallel-grouped, two arm, double-blinded, randomized controlled trial (RCT) that included 28 patients (n = 28) with stage-III grade B periodontitis, who were allocated randomly to test- (CLN/I-PRF + M-MIST, 50 μL of CLN per 1 mL of I-PRF; n = 14) or control-group (I-PRF + M-MIST; n = 14). Clinical attachment level (CAL; primary outcome), probing depth (PD), gingival margin level (GML), plaque index (PI), and gingival index (GI) were recorded at baseline, 3, 6, and 9 months, whereas radiographic parameters radiographic linear defect depth (RLDD), and radiographic defect area (RDA) were recorded at baseline, 6, and 9 months. The CLN release kinetics from the I-PRF were further characterized.

RESULTS

Compared to baseline, both groups independently demonstrated significant improvements in CAL, PD, GML, GI, PI, RLDD and BDA at 3, 6 and 9 months (p < .05). A significant reduction in CAL measurements was noticeable in the CLN/I-PRF + M-MIST and I-PRF + M-MIST group independently over time (p < .05). CLN/I-PRF + M-MIST showed significantly lower CAL than PRF + M-MIST group at baseline, after three as well as 9 months (p < .05). Intergroup comparisons at 9 months demonstrated that CAL-gain was non-significant between groups (p > .05), GI significantly lower in CLN/I-PRF + M-MIST, whereas PD-reduction significantly higher I-PRF + M-MIST group (p < .05). CLN was steadily released for the I-PRF for up to 48 h, with a peak concentration at 24 h, which then gradually declined till the seventh day.

CONCLUSIONS

I-PRF with M-MIST provided significant clinical and radiographic improvement up to 9 months postoperatively in stage-III grade B periodontitis. CLN, at the applied concentration and release duration, does not appear to further positively impact these observed I-PRF effects.

Evaluation of antimicrobial activity of platelet-rich fibrin and titanium platelet-rich fibrin with and without incorporation of antibiotics on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans: An in vitro study

Background

Infection control is of paramount importance after any periodontal therapy to achieve proper wound healing and regeneration of periodontal tissues. Clinicians continuously strive to provide procedures and/or materials that allow for enhanced and rapid wound healing. The regenerative potential of platelet concentrates like platelet-rich fibrin (PRF) has been explored for their anti-inflammatory action and liberation of growth factors; however, research is lacking on the antibacterial properties of platelet-rich gels. The present in vitro study was done to assess the antimicrobial activity of PRF and titanium PRF (T-PRF) alone or with antibiotics on periodontal pathogens.

Materials and Methods

Thirty-three individuals who were willing to donate blood (12 ml) were included in the study. Amoxicillin (AMOX) + metronidazole (METRO) combination or clindamycin (CLINDA) was incorporated into the blood drawn, and this blood was subjected to centrifugation so as to obtain T-PRF and PRF with antibiotics. The antibacterial activity of all the groups was tested on both bacteria that were cultured in their respective media for up to a 4-day period. The data were subjected to independent t-test, Tukey post hoc test, repeated analysis of variance (ANOVA), and ANOVA.

Results

All individual parameters were compared for antimicrobial activity on both bacteria on all 4 days. A highly statistical difference (P = 0.0001) was observed in all the groups, with the highest inhibition zone produced by PRF-CLINDA, followed by T-PRF-CLINDA. Antimicrobial activity was evident for the observed 4-day period, which declined from day 1 to day 4.

Conclusion

T-PRF/PRF with and without antibiotics exhibited antimicrobial activity on Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis over the observed 4-day period.

The impact of local and systemic penicillin on antimicrobial properties and growth factor release in platelet-rich fibrin: In vitro study

OBJECTIVE

This study evaluates the impact of local and systemic administration of penicillin on the antimicrobial properties and growth factors of platelet-rich fibrin (PRF) under in vitro conditions.

MATERIALS AND METHODS

The study involved 12 volunteers. Four tubes of venous blood were collected before systemic antibiotic administration. Two tubes were centrifuged at 2700 RPM for 12 min to obtain PRF, while 0.2 ml of penicillin was locally added into other two tubes. After systemic administration, blood samples were again collected and subjected to centrifugation. The release of growth factors (IGF-1, PDGF, FGF-2, and TGFβ-1) was determined using the Enzyme-Linked Immunosorbent Assay (ELISA), and an antibiotic sensitivity test was performed for S. aureus and E. coli bacteria.

RESULTS

Results showed that local antibiotic addition before PRF centrifugation had a significant antimicrobial effect without affecting growth factor releases. There was no statistically significant difference in antimicrobial properties between PRF prepared with systemic antibiotic administration and PRF prepared without antibiotics.

MATERIALS AND METHODS

The study suggests that incorporating localized antibiotics into PRF results in strong antimicrobial effects without compromise of growth factor release. However, the combination of PRF with systemic antibiotics did not significantly enhance its antimicrobial properties compared to PRF prepared without antibiotics.

CLINICAL RELEVANCE

Local addition of penicillin into PRF provides strong antimicrobial properties which may help reduce dependence on systemic antibiotic regimens, mitigating antibiotic resistance and minimizing associated side effects.

Platelet-rich gel versus external tissue expansion technique in treating scalp defects: A retrospective study

Reconstruction of scalp defects is a complicated and challenging procedure for reconstructive surgeons. This retrospective observational study assessed the effectiveness of using platelet-rich gel (PRG) versus the external tissue expansion technique (TET) in reconstructing scalp defects. The clinical data of 24 patients with scalp defects treated with PRG or external TET were collected from September 2018 to March 2022. Data on the wound characteristics, wound healing time, cost of treatment, visual analog scale, and observed wound healing status were collected. The mean wound healing times in the PRG and TET groups were 25.00 ± 5.77 and 13.58 ± 9.68 days, respectively (P < .05). The PRG group was significantly more cost-effective than the TET group (P < .05). TET treatment significantly increased patients' postoperative pain, which decreased over time (P < .05), while PRG treatment caused no significant change in pain (P > .05). The 2 groups showed no tissue depression or color change after wound healing at follow-up, but the hair growth in the TET group was significantly better than that in the PRG group (P < .05). Compared with TET treatment of scalp defects, PRG is not only simple and painless but also has a low treatment cost and, more importantly, does not involve the risk of surgery and anesthesia. However, using TET to treat scalp defects requires the careful selection of appropriate cases.

An injectable bioactive dressing based on platelet-rich plasma and nanoclay: Sustained release of deferoxamine to accelerate chronic wound healing

Delayed diabetic wound healing has placed an enormous burden on society. The key factors limiting wound healing include unresolved inflammation and impaired angiogenesis. Platelet-rich plasma (PRP) gel, a popular biomaterial in the field of regeneration, has limited applications due to its non-injectable properties and rapid release and degradation of growth factors. Here, we prepared an injectable hydrogel (DPLG) based on PRP and laponite by a simple one-step mixing method. Taking advantages of the non-covalent interactions, DPLG could overcome the limitations of PRP gels, which is injectable to fill irregular injures and could serve as a local drug reservoir to achieve the sustained release of growth factors in PRP and deferoxamine (an angiogenesis promoter). DPLG has an excellent ability in accelerating wound healing by promoting macrophage polarization and angiogenesis in a full-thickness skin defect model in type I diabetic rats and normal rats. Taken together, this study may provide the ingenious and simple bioactive wound dressing with a superior ability to promote wound healing.

Combining the dual antibacterial and regenerative activities of platelet-rich plasma with β-lactams to mitigate MRSA-infected skin wounds

The emergence of multidrug-resistant bacteria contributes to the necessity of developing novel infection treatment approaches. This study was designed to evaluate the antimicrobial and wound healing activities of platelet-rich plasma (PRP) in combination with β-lactams (ampicillin and/or oxacillin) for the application on methicillin-resistant Staphylococcus aureus (MRSA)-infected skin. PRP was collected from the peripheral blood of healthy donors. The anti-MRSA activity was tested through a growth inhibition curve, colony-forming unit (CFU), and SYTO 9 assay. The PRP incorporation lowered the minimum inhibitory concentration (MIC) of ampicillin and oxacillin against MRSA. The combination of β-lactams together with PRP showed a three-log CFU reduction of MRSA. The major components of PRP for eliminating MRSA were found to be the complement system and iron sequestration proteins, according to the proteomic analysis. The adhesive bacterial colony in the microplate was decreased from 2.9 × 107 to 7.3 × 105 CFU after the treatment of cocktails containing β-lactams and PRP. The cell-based study indicated that keratinocyte proliferation was stimulated by PRP. The in vitro scratch and transwell experiments revealed that PRP improved keratinocyte migration. In the MRSA-infected mouse skin model, PRP appeared to show a synergistic effect for wound area reduction by 39% when combined with β-lactams. The MRSA burden in the infected area was lessened two-fold after topical administration of the combined β-lactams and PRP. PRP inhibited macrophage infiltration in the wound site to shorten the inflammatory phase and accelerate the initiation of the proliferative phase. No skin irritation was detected with the topical delivery of this combination. Our findings suggested that β-lactams plus PRP was applicable to alleviate the problems associated with MRSA via dual antibacterial and regenerative activities.

Effects of platelet-rich plasma on corneal re-epithelization and metalloproteinase expression in the cornea of sheep with experimentally-induced infectious keratoconjunctivitis

Background and Aim

Infectious bovine keratoconjunctivitis is the most crucial ophthalmic disease among ruminants worldwide. Moraxella is the bacteria generally associated with this disease and leads to keratitis, conjunctivitis, corneal ulcers, or blindness. Platelet-rich plasma (PRP) effects in corneal ulcers and different ocular superficial diseases in animals and humans are beneficial and enhance rapid healing and improvement, but the effects in infectious keratoconjunctivitis in ruminants are uncertain. This study aimed to examine the effect of PRP on re-epithelization, corneal tissue, clinical signs, and matrix metalloproteinase (MMP) expression in sheep with infectious keratoconjunctivitis.

Materials and Methods

Eighteen sheep were divided into three groups and subjected to a disease-induction experiment. Group 1 (G1) was administered 1.0 mL PRP subconjunctivally, Group 2 (G2) was administered 1.0 mL PRP subconjunctivally and 50 μL gentamicin drops, and the control group (CG) was administered 50 μL saline solution topically every 12 h. Clinical ophthalmologic examination, fluorescein staining, and photography were carried out. Ulcerated areas were measured employing J-Image software. Five and eleven days following the procedure, half of the animals from each group were euthanized, and their corneas were evaluated by histopathology and zymography.

Results

Control Group and G2 epithelialized more rapidly. The CG exhibited fewer clinical signs of ocular disease. In histopathological analysis, in G2, alterations were observed only in the epithelium. The CG and G1 exhibited alterations in the epithelium, stroma, and Descemet's membrane. In zymography, a decline in MMP-2 expression in the animals treated with PRP was detected. Matrix metalloproteinase-9 was significantly expressed in the animals treated with PRP monotherapy, whereas PRP + gentamicin and CG caused a decrease.

Conclusion

Platelet-rich plasma alone did not demonstrate any beneficial effect on re-epithelialization, a decline in clinical signs, tissue alterations, and expression of metalloproteinases. Platelet-rich plasma combined with gentamicin was capable of suppressing MMPs, primarily MMP-9, but do not display positive effects in re-epithelization, reduction of clinical signs, or tissue effects. These outcomes are similar to those discovered in untreated animals, so the use of PRP in patients with infectious keratoconjunctivitis does not offer greater benefits in sheep. Additional research is required to validate the results of PRP use in natural disease presentation.

Can platelet-rich fibrin act as a natural carrier for antibiotics delivery? A proof-of-concept study for oral surgical procedures

OBJECTIVES

Evaluate the role of platelet-rich fibrin (PRF) as a natural carrier for antibiotics delivery through the analysis of drug release and antimicrobial activity.

MATERIALS AND METHODS

PRF was prepared according to the L-PRF (leukocyte- and platelet-rich fibrin) protocol. One tube was used as control (without drug), while an increasing amount of gentamicin (0.25 mg, G1; 0.5 mg, G2; 0.75 mg, G3; 1 mg, G4), linezolid (0.5 mg, L1; 1 mg, L2; 1.5 mg, L3; 2 mg, L4), vancomycin (1.25 mg, V1; 2.5 mg, V2; 3.75 mg, V3; 5 mg, V4) was added to the other tubes. At different times the supernatant was collected and analyzed. Strains of E. coli, P. aeruginosa, S. mitis, H. influenzae, S. pneumoniae, S. aureus were used to assess the antimicrobial effect of PRF membranes prepared with the same antibiotics and compared to control PRF.

RESULTS

Vancomycin interfered with PRF formation. Gentamicin and linezolid did not change the physical properties of PRF and were released from membranes in the time intervals examined. The inhibition area analysis showed that control PRF had slight antibacterial activity against all tested microorganisms. Gentamicin-PRF had a massive antibacterial activity against all tested microorganisms. Results were similar for linezolid-PRF, except for its antibacterial activity against E. coli and P. aeruginosa that was comparable to control PRF.

CONCLUSIONS

PRF loaded with antibiotics allowed the release of antimicrobial drugs in an effective concentration. Using PRF loaded with antibiotics after oral surgery may reduce the risk of post-operative infection, replace or enhance systemic antibiotic therapy while preserving the healing properties of PRF. Further studies are needed to prove that PRF loaded with antibiotics represents a topical antibiotic delivery tool for oral surgical procedures.

Enhanced Bioactive Potential of Functionalized Injectable Platelet-Rich Plasma

Injectable platelet-rich fibrin (iPRF) is a frequently used platelet concentrate used for various medical purposes both in veterinary and human medicine due to the regenerative potential of hard and soft tissues, and also because of its antimicrobial effectiveness. This in vitro study was carried out to assess the cumulative antimicrobial and antibiofilm effect of iPRF functionalized with a multifunctional glycoprotein, human lactoferrin (Lf). Thus, the ability to potentiate cell proliferation was tested on keratinocytes and evaluated by the CCK8 test. The combinations of iPRF and Lf induced an increase in the proliferation rate after 24 h. The average cell viability of treated cultures (all nine variants) was 102.87% ± 1.00, and the growth tendency was maintained even at 48 h. The highest proliferation rate was observed in cultures treated with 7% iPRF in combination with 50 µg/mL of Lf, with an average viability of 102.40% ± 0.80. The antibacterial and antibiofilm activity of iPRF, of human lactoferrin and their combination were tested by agar-well diffusion (Kirby-Bauer assay), broth microdilution, and crystal violet assay against five reference bacterial strains. iPRF showed antimicrobial and antibiofilm potential, but with variations depending on the tested bacterial strain. The global analysis of the results indicates an increased antimicrobial potential at the highest concentration of Lf mixed with iPRF. The study findings confirmed the hypothesized enhanced bioactive properties of functionalized iPRF against both Gram-positive and Gram-negative biofilm-producing bacteria. These findings could be further applied, but additional studies are needed to evaluate the mechanisms that are involved in these specific bioactive properties.

Blood cell-based drug delivery systems: a biomimetic platform for antibacterial therapy

With the rapid increase in multidrug-resistance against antibiotics, higher doses of antibiotics or more effective antibiotics are needed to treat diseases, which ultimately leads to a decrease in the body's immunity and seriously threatens human health worldwide. The efficiency of antibiotics has been a large challenge for years. To overcome this problem, many carriers are utilized for anti-bacteria, attempting to optimize the delivery of such drugs and transport them safely and directly to the site of disease. Blood cell-based drug delivery systems present several advantages as compared to polymeric delivery system. These blood cells including red blood cells (RBCs), leukocytes, platelets. The blood cells and their membranes can both be used as drug carriers to deliver antibacterial drugs. In addition, blood cells can overcome many physiological/pathological obstacles faced by nanoparticles in vivo and effectively deliver drugs to the site of the disease. In this paper, we review studies on blood cell-based delivery systems used in antibacterial therapy, and analyze different roles in antibacterial therapy, which provide basis for further study in this field.

Injectable Platelet-Rich Fibrin as a Drug Carrier Increases the Antibacterial Susceptibility of Antibiotic—Clindamycin Phosphate

The aim of this study was to investigate the change in clindamycin phosphate antibacterial properties against Gram-positive bacteria using the platelet-rich fibrin as a carrier matrix, and evaluate the changes in the antibiotic within the matrix. The antibacterial properties of CLP and its combination with PRF were tested in a microdilution test against reference cultures and clinical isolates of Staphylococcus aureus (S. aureus) or Staphylococcus epidermidis (S. epidermidis). Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) analysis was done to evaluate the changes in the PRF_CLP matrix. Release kinetics of CLP was defined with ultra-performance liquid chromatography (UPLC). According to FTIR data, the use of PRF as a carrier for CLP ensured the structural changes in the CLP toward a more active form of clindamycin. A significant decrease in minimal bactericidal concentration values (from 1000 µg/mL to 62 µg/mL) against reference cultures and clinical isolates of S. aureus and S. epidermidis was observed for the CLP and PRF samples if compared to pure CLP solution. In vitro cell viability tests showed that PRF and PRF with CLP have higher cell viability than 70% after 24 h and 48 h time points. This article indicates that CLP in combination with PRF showed higher antibacterial activity against S. aureus and S. epidermidis compared to pure CLP solution. This modified PRF could be used as a novel method to increase drug delivery and efficacy, and to reduce the risk of postoperative infection.

Impact of local and systemic antimicrobials on leukocyte- and platelet rich fibrin: an in vitro study

The aim of this study was to evaluate the effect of local and systemic administration of antimicrobials to leukocyte- and platelet-rich fibrin (L-PRF). For part A, 16 tubes of venous blood were collected from each of eight systemically healthy subjects. Prior to blood centrifugation, 12 of the 16 tubes were injected with 0.125 ml, 0.25 ml or 0.50 ml metronidazole solution. One set of L-PRF membranes was used to assess the release of vascular endothelial growth factor AB, platelet-derived growth factor, transforming growth factor beta 1, and bone morphogenetic protein 2 at indicated time points. The metronidazole release over time by L-PRF membranes was also evaluated. The remaining L-PRF membranes were placed on the surface of agar plates inoculated with three different periodontal pathogens to determine their antibacterial activity. For part B, another six subjects were enrolled with three subjects taking 2 g amoxicillin and three subjects 500 mg metronidazole as prophylaxis prior to a periodontal treatment. Before and 2 h after consuming one of the prescribed antimicrobials, three tubes of blood were collected for preparing L-PRF membranes. These membranes were used to measure the antibacterial activity against periodontal pathogens. No statistically significant difference could be found in the release of growth factors between L-PRF membranes with and without incorporation of metronidazole solution. The release of metronidazole could be detected up to day 3, however with the highest concentration during the first 4 h. This concentration was dose dependent. The antibacterial capacity of L-PRF membranes increased significantly for both the systemic intake, and after the addition of metronidazole solution to the blood tubes before centrifugation, the latter again dose dependent. The antibacterial capacity of L-PRF against the periodontal pathogens tested can significantly be enhanced by the addition of antimicrobials, without disadvantage for the release of growth factors.

Application of platelet-rich plasma in traumatic bone infections

Introduction: Traumatic bone infection represents a clinical challenge for orthopedic surgeons. Traditional treatments include surgical debridement and antibiotic, but prolonged use of antibiotic may lead to colonization of resistant bacteria and other adverse reactions.Areas covered: Platelet-rich plasma (PRP), a biological product extracted from the peripheral blood of patients, has been widely used in the field of tissue repair in recent years. Because if its structural and antibacterial properties, PRP is an innovative option for the prevention and treatment of infections. This review assesses the recent scientific literature on PRP, specifically its in the treatment of infections. To this end, a literature review was conducted using the PubMed and Web of Science databases with the following keywords 'platelet-rich plasma (PRP)'; 'PRP AND traumatic bone infections'; 'PRP AND bone defect'; 'PRP AND antibiotics'; and 'PRP AND wound healing'.Expert opinion: This review focuses on the mechanism of action, preparation methods, clinical applications and other aspects related to PRP to provide a reference for its use in the treatment of traumatic bone infections, thereby enhancing the therapeutic effectiveness and improving the prognosis of patients.

Hydrogel Containing Anti-CD44-Labeled Microparticles, Guide Bone Tissue Formation in Osteochondral Defects in Rabbits

Hydrogels are suitable for osteochondral defect regeneration as they mimic the viscoelastic environment of cartilage. However, their biomechanical properties are not sufficient to withstand high mechanical forces. Therefore, we have prepared electrospun poly-ε-caprolactone-chitosan (PCL-chit) and poly(ethylene oxide)-chitosan (PEO-chit) nanofibers, and FTIR analysis confirmed successful blending of chitosan with other polymers. The biocompatibility of PCL-chit and PEO-chit scaffolds was tested; fibrochondrocytes and chondrocytes seeded on PCL-chit showed superior metabolic activity. The PCL-chit nanofibers were cryogenically grinded into microparticles (mean size of about 500 µm) and further modified by polyethylene glycol-biotin in order to bind the anti-CD44 antibody, a glycoprotein interacting with hyaluronic acid (PCL-chit-PEGb-antiCD44). The PCL-chit or PCL-chit-PEGb-antiCD44 microparticles were mixed with a composite gel (collagen/fibrin/platelet rich plasma) to improve its biomechanical properties. The storage modulus was higher in the composite gel with microparticles compared to fibrin. The Eloss of the composite gel and fibrin was higher than that of the composite gel with microparticles. The composite gel either with or without microparticles was further tested in vivo in a model of osteochondral defects in rabbits. PCL-chit-PEGb-antiCD44 significantly enhanced osteogenic regeneration, mainly by desmogenous ossification, but decreased chondrogenic differentiation in the defects. PCL-chit-PEGb showed a more homogeneous distribution of hyaline cartilage and enhanced hyaline cartilage differentiation.