MESOBLAST ENTERS INTO OPTION TO ISSUE US$50 MILLION CONVERTIBLE NOTES Melbourne, Australia; September 4 and New York, USA; September 3, 2025: Mesoblast Limited (ASX:MSB; Nasdaq:MESO), global leader in allogeneic cellular medicines for inflammatory diseases, today announced it has entered into convertible note subscription agreements with SurgCenter principals and existing Mesoblast shareholders, Gregory George and William Gueck (“Investors”) to issue, at its sole discretion, up to US$50.0 million (A$76.8 million)1 of unsecured convertible notes. The funding is available at Mesoblast’s option, following shareholder approval, to repay or reduce the amount owing to its secured lenders under the existing loan agreements and for general working capital purposes. Mesoblast Chief Executive Silviu Itescu said: “We appreciate the ongoing support from our major shareholders in ensuring that the Company can optimize its capital structure and support our ongoing pipeline growth opportunities.” Key terms of the Convertible Notes Mesoblast at its sole discretion, subject to shareholder approval at the upcoming Annual General Meeting (AGM), may issue up to US$50 million of unsecured convertible notes in tranches of US$10 million to the Investors. The maturity date of the convertible notes will be 5 years after the first issuance of notes (unless redeemed or converted earlier). At any time up to the maturity date, the Investors may elect to convert the notes issued into fully paid ordinary shares or ADRs of Mesoblast at the conversion price of US$16.25 per ADR (American Depositary Receipt) equivalent to A$2.501 per ASX-listed share, representing 126% of Mesoblast’s last closing price on Nasdaq and a 29% premium to the last closing price on the ASX. The convertible notes have a coupon of 5% per annum on the face value of issued notes. As consideration, the Investors collectively will receive a commitment fee of US$100,000 and, subject to shareholder approval, of 2 million warrants over 2 million ordinary shares (or 200,000 Mesoblast ADRs) for entering into the convertible note option, and a further 3 million warrants over 3 million ordinary shares (or 300,000 Mesoblast ADRs) should Mesoblast exercise this option. The warrants shall have the same exercise price as the conversion price of the notes and a maturity date of 4 years from the date of first issuance of the warrants. The conversion price is subject to adjustment mechanisms in the event of future share issues, capital reductions, share consolidations and other corporate actions in accordance with customary adjustment rules. 1 Using an exchange rate of 1A$:0.65US$. About Mesoblast Mesoblast (the Company) is a world leader in developing allogeneic (off-the-shelf) cellular medicines for the treatment of severe and life-threatening inflammatory conditions. The therapies from the Company’s proprietary mesenchymal lineage cell therapy technology platform respond to severe inflammation by releasing anti-inflammatory factors that counter and modulate multiple effector arms of the immune system, resulting in significant reduction of the damaging inflammatory process. Mesoblast’s Ryoncil® (remestemcel-L-rknd) for the treatment of steroid-refractory acute graft versus host disease (SR-aGvHD) in pediatric patients 2 months and older is the first FDA-approved mesenchymal stromal cell (MSC) therapy. Please see the full Prescribing Information at www.ryoncil.com. Mesoblast is committed to developing additional cell therapies for distinct indications based on its remestemcel-L and rexlemestrocel-L allogeneic stromal cell technology platforms. Ryoncil® is being developed for additional inflammatory diseases including SR-aGvHD in adults and biologic-resistant inflammatory bowel disease. Rexlemestrocel-L is being developed for heart failure and chronic low back pain. The Company has established commercial partnerships in Japan, Europe and China.

About Mesoblast intellectual property: Mesoblast has a strong and extensive global intellectual property portfolio, with over 1,000 granted patents or patent applications covering mesenchymal stromal cell compositions of matter, methods of manufacturing and indications. These granted patents and patent applications are expected to provide commercial protection extending through to at least 2041 in major markets. About Mesoblast manufacturing: The Company’s proprietary manufacturing processes yield industrial-scale, cryopreserved, off-the-shelf, cellular medicines. These cell therapies, with defined pharmaceutical release criteria, are planned to be readily available to patients worldwide. Mesoblast has locations in Australia, the United States and Singapore and is listed on the Australian Securities Exchange (MSB) and on the Nasdaq (MESO). For more information, please see www.mesoblast.com, LinkedIn: Mesoblast Limited and Twitter: @Mesoblast Forward-Looking Statements This press release includes forward-looking statements that relate to future events or our future financial performance and involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to differ materially from any future results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. We make such forward-looking statements pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. Forward-looking statements should not be read as a guarantee of future performance or results, and actual results may differ from the results anticipated in these forward-looking statements, and the differences may be material and adverse. Forward-looking statements include, but are not limited to, statements about: the initiation, timing, progress and results of Mesoblast’s preclinical and clinical studies, and Mesoblast’s research and development programs; Mesoblast’s ability to advance product candidates into, enroll and successfully complete, clinical studies, including multi-national clinical trials; Mesoblast’s ability to advance its manufacturing capabilities; the timing or likelihood of regulatory filings and approvals, manufacturing activities and product marketing activities, if any; the commercialization of Mesoblast’s Ryoncil® for pediatric SR-aGVHD and any other product candidates, if approved; regulatory or public perceptions and market acceptance surrounding the use of stem-cell based therapies; the potential for Mesoblast’s product candidates, if any are approved, to be withdrawn from the market due to patient adverse events or deaths; the potential benefits of strategic collaboration agreements and Mesoblast’s ability to enter into and maintain established strategic collaborations; Mesoblast’s ability to establish and maintain intellectual property on its product candidates and Mesoblast’s ability to successfully defend these in cases of alleged infringement; the scope of protection Mesoblast is able to establish and maintain for intellectual property rights covering its product candidates and technology; estimates of Mesoblast’s expenses, future revenues, capital requirements and its needs for additional financing; Mesoblast’s financial performance; developments relating to Mesoblast’s competitors and industry; and the pricing and reimbursement of Mesoblast’s product candidates, if approved. You should read this press release together with our risk factors, in our most recently filed reports with the SEC or on our website. Uncertainties and risks that may cause Mesoblast’s actual results, performance or achievements to be materially different from those which may be expressed or implied by such statements, and accordingly, you should not place undue reliance on these forward-looking statements. We do not undertake any obligations to publicly update or revise any forward-looking statements, whether as a result of new information, future developments or otherwise. Release authorized by the Chief Executive. For more information, please contact: Corporate Communications / Investors Paul Hughes T: +61 3 9639 6036 Media – Global

Allison Worldwide Emma Neal T: +1 603 545 4843 E: emma.neal@allisonworldwide.com Media – Australia BlueDot Media Steve Dabkowski T: +61 419 880 486 E: steve@bluedot.net.au

Appendix 3B - Proposed issue of securities Appendix 3B - Proposed issue of securities 1 / 5 Announcement Summary Entity name MESOBLAST LIMITED Announcement Type New announcement Date of this announcement 4/9/2025 The Proposed issue is: Total number of +securities proposed to be issued for a placement or other type of issue ASX +security code +Security description Maximum Number of +securities to be issued New class-code to be confirmed WARRANTS 3 5,000,000 Proposed +issue date 1/12/2025 Refer to next page for full details of the announcement A placement or other type of issue

Appendix 3B - Proposed issue of securities Appendix 3B - Proposed issue of securities 2 / 5 Part 1 - Entity and announcement details 1.1 Name of +Entity MESOBLAST LIMITED We (the entity named above) give ASX the following information about a proposed issue of +securities and, if ASX agrees to +quote any of the +securities (including any rights) on a +deferred settlement basis, we agree to the matters set out in Appendix 3B of the ASX Listing Rules. If the +securities are being offered under a +disclosure document or +PDS and are intended to be quoted on ASX, we also apply for quotation of all of the +securities that may be issued under the +disclosure document or +PDS on the terms set out in Appendix 2A of the ASX Listing Rules (on the understanding that once the final number of +securities issued under the +disclosure document or +PDS is known, in accordance with Listing Rule 3.10.3C, we will complete and lodge with ASX an Appendix 2A online form notifying ASX of their issue and applying for their quotation). 1.2 Registered Number Type ABN Registration Number 68109431870 1.3 ASX issuer code MSB 1.4 The announcement is 1.5 Date of this announcement 4/9/2025 1.6 The Proposed issue is: A placement or other type of issue New announcement

Appendix 3B - Proposed issue of securities Appendix 3B - Proposed issue of securities 3 / 5 Part 7 - Details of proposed placement or other issue Part 7A - Conditions 7A.1 Do any external approvals need to be obtained or other conditions satisfied before the placement or other type of issue can proceed on an unconditional basis? 7A.1a Conditions Approval/Condition +Security holder approval Date for determination 7/11/2025 Is the date estimated or actual? ** Approval received/condition met?   Comments Part 7B - Issue details Is the proposed security a 'New class' (+securities in a class that is not yet quoted or recorded by ASX) or an 'Existing class' (additional securities in a class that is already quoted or recorded by ASX)? Will the proposed issue of this +security include an offer of attaching +securities? Details of +securities proposed to be issued ISIN Code (if Issuer is a foreign company and +securities do not have +CDIs issued over them)   Have you received confirmation from ASX that the terms of the proposed +securities are appropriate and equitable under listing rule 6.1? Will the entity be seeking quotation of the 'new' class of +securities on ASX? ASX +security code New class-code to be confirmed +Security description WARRANTS 3 +Security type Options Number of +securities proposed to be issued 5,000,000 Offer price details No No No New class Estimated Yes

Appendix 3B - Proposed issue of securities Appendix 3B - Proposed issue of securities 4 / 5 Offer price details Are the +securities proposed to be issued being issued for a cash consideration? Please describe the consideration being provided for the +securities In connection with the availability of the up to US$50 million convertible note facility, which the Company can use at its option following shareholder approval, announced by the Company on 4 September 2025. Please note, 3 million warrants will only vest if the Company exercises its option under the convertible note facility. Please provide an estimate of the AUD equivalent of the consideration being provided for the +securities   Will all the +securities issued in this class rank equally in all respects from their issue date? Options details +Security currency AUD - Australian Dollar Exercise price AUD 2.5000 Expiry date 1/12/2029 Details of the type of +security that will be issued if the option is exercised MSB : ORDINARY FULLY PAID Number of securities that will be issued if the option is exercised 1 ordinary share. The warrants can also be converted to American Depositary Receipts (ADRs), in which case 10 warrants will convert into 1 ADR at an exercise price of US$16.25 per ADR. Please provide a URL link for a document lodged with ASX setting out the material terms of the +securities proposed to be issued or provide the information by separate announcement. See announcement lodged with the ASX on 4 September 2025. For more information on Mesoblast American Depositary Receipts, please see our Preliminary Final Report including Appendix 4E lodged with the ASX on 29 August 2025. Please note, 3 million warrants will only vest if the Company exercises its option under the convertible note facility. Part 7C - Timetable 7C.1 Proposed +issue date 1/12/2025 Part 7D - Listing Rule requirements 7D.1 Has the entity obtained, or is it obtaining, +security holder approval for the entire issue under listing rule 7.1? 7D.1b Are any of the +securities proposed to be issued without +security holder approval using the entity's 15% No Yes No

Appendix 3B - Proposed issue of securities Appendix 3B - Proposed issue of securities 5 / 5 7D.1b Are any of the +securities proposed to be issued without +security holder approval using the entity's 15% placement capacity under listing rule 7.1? 7D.1b ( i ) How many +securities are proposed to be issued without security holder approval using the entity's 15% placement capacity under listing rule 7.1? 1,000,000 7D.1c Are any of the +securities proposed to be issued without +security holder approval using the entity's additional 10% placement capacity under listing rule 7.1A (if applicable)? 7D.2 Is a party referred to in listing rule 10.11 participating in the proposed issue? 7D.3 Will any of the +securities to be issued be +restricted securities for the purposes of the listing rules? 7D.4 Will any of the +securities to be issued be subject to +voluntary escrow? Part 7E - Fees and expenses 7E.1 Will there be a lead manager or broker to the proposed issue? 7E.2 Is the proposed issue to be underwritten? 7E.4 Details of any other material fees or costs to be incurred by the entity in connection with the proposed issue Part 7F - Further Information 7F.01 The purpose(s) for which the entity is issuing the securities In connection with the availability of the up to US$50 million convertible note facility, which the Company can use at its option following shareholder approval, announced by the Company on 4 September 2025. 7F.1 Will the entity be changing its dividend/distribution policy if the proposed issue proceeds? 7F.2 Any other information the entity wishes to provide about the proposed issue No No No No No Yes No Yes